From e0c6872cf40896c7be36b11dcc744620f10adf1d Mon Sep 17 00:00:00 2001
From: Norbert Preining <norbert@preining.info>
Date: Mon, 2 Sep 2019 13:46:59 +0900
Subject: Initial commit

---
 .../contrib/springer/svjour/stropt/natbib.dtx      | 3221 ++++++++++++++++++++
 1 file changed, 3221 insertions(+)
 create mode 100644 macros/latex/contrib/springer/svjour/stropt/natbib.dtx

(limited to 'macros/latex/contrib/springer/svjour/stropt/natbib.dtx')

diff --git a/macros/latex/contrib/springer/svjour/stropt/natbib.dtx b/macros/latex/contrib/springer/svjour/stropt/natbib.dtx
new file mode 100644
index 0000000000..33bdffdaca
--- /dev/null
+++ b/macros/latex/contrib/springer/svjour/stropt/natbib.dtx
@@ -0,0 +1,3221 @@
+% \iffalse      THIS IS A META-COMMENT
+%<*dtx>
+\ProvidesFile
+%========================================================================
+                       {NATBIB.DTX}
+%========================================================================
+%</dtx>
+% This is a LaTeX package to modify \cite and \thebibliography for author-year 
+%    systems of bibliographic citation; will also work with 
+%    numerical systems, allowing simplified style changes for them too.
+% Installation:
+%    LaTeX this file: creates docstrip installation file natbib.ins
+%                         AND the (LaTeX2e) documentation
+%    (La)TeX natbib.ins: creates package file natbib.sty 
+%                        and optionally the LaTeX 2.09 style natbib209.sty
+%                        and doc driver natbib.drv
+%    (natbib.ins may be edited as needed)
+% Docstrip options available:
+%        package - to produce a (LaTeX2e) package .sty file 
+%        driver  - to produce a driver file to print the documentation
+%        209     - (with package) for style file that runs under LaTeX 2.09 
+%        subpack - (with package) for coding included in other packages
+%        all     - (with package) to include all author-year systems
+%                   else individually with:
+%        apalike, newapa, chicago, harvard, authordate, astron
+%        agu     - (with package,subpack) for inclusion in aguplus package
+%        egs- (with package,subpack) for inclusion in egs package
+%        nopreonly - allows \citestyle and \bibpunct to be used anywhere
+%--------------------------------------------------------------------------
+%<*!subpack>
+%<package&209>\def\ProvidesPackage#1#2]
+%<package&209>  {\typeout{Style option `#1'#2]}}
+%
+%  *** Identify the package file:-
+%<package&!209>\NeedsTeXFormat{LaTeX2e}[1994/06/01]
+%<package>\ProvidesPackage{natbib}
+%</!subpack>
+%
+%  *** Provide command to dislay module version
+%<package&subpack>\def\ModuleVersion#1[#2]{}
+%<package&subpack>    \ModuleVersion{natbib}
+%
+%  *** Identify the driver file:-
+%<driver>\NeedsTeXFormat{LaTeX2e}
+%<driver>\ProvidesFile{natbib.drv}
+%
+%  *** The DATE, VERSION, and other INFO
+%\fi
+%\ProvidesFile{natbib}
+        [1997/02/05 6.5 (PWD)]
+%\iffalse
+%<*package>
+%<*!subpack>
+%%-------------------------------------------------------------------
+%% NOTICE:
+%% This file may be used for non-profit purposes.
+%% It may not be distributed in exchange for money, 
+%%   other than distribution costs.
+%%   
+%% The author provides it `as is' and does not guarantee it in any way.
+%% 
+%</!subpack>
+%</package>
+%% Natbib coding copyright (C) 1994--1997 Patrick W. Daly
+%<*package>
+%<*!subpack>
+%% Max-Planck-Institut f\"ur Aeronomie
+%% Postfach 20
+%% D-37189 Katlenburg-Lindau
+%% Germany
+%% 
+%% E-mail:
+%% Internet-- daly@linmpi.dnet.gwdg.de   
+%%-----------------------------------------------------------
+%</!subpack>
+%</package>
+%                    END META-COMMENT \fi
+% \changes{4.0}{1993 Aug 19}{First documented release}
+% \changes{4.1}{1993 Oct 4}{Simplification of \cs{@citeapalk}}
+% \changes{4.1a}{1993 Oct 14}{Add \texttt{rev} option for reversed comments 
+%                             in \cs{cite}}
+% \changes{4.1b}{1993 Oct 18}{Add \cs{bibfont} to list definition =\cs{relax}}
+% \changes{4.2}{1993 Oct 22}{Add coding for AGU, NLINPROC}
+% \changes{4.2}{1993 Nov 20}{Add more coding for AGU}
+% \changes{4.3a}{1994 Feb 24}{First additions for \LaTeXe}
+% \changes{5.0}{1994 May 18}{Revised for \LaTeXe{} and 2.09}
+% \changes{5.0}{1994 May 18}{Remove obsolete JGR, GRL coding}
+% \changes{5.0}{1994 May 18}{Add \cs{citeauthor}, \cs{citeyear}}
+% \changes{5.0}{1994 May 18}{Two optional texts for \cs{cite} so \texttt{rev}
+%                            option obsolete}
+% \changes{5.0}{1994 May 18}{\LaTeXe\ options to select punctuation}
+% \changes{5.1}{1994 Jun 22}{Conform to first official release of \LaTeXe}
+% \changes{5.1}{1994 Jun 22}{Separate \LaTeX\ and 2.09 files}
+% \changes{5.1}{1994 Jun 22}{Put doc driver first}
+% \changes{5.2}{1994 Aug 25}{Fix up 2.09 style to run in compatibility mode}
+% \changes{5.2}{1994 Aug 25}{\cs{citeauthor}, \cs{citeyear} make BibTeX 
+%                             entry in aux file}
+% \changes{5.2}{1994 Aug 25}{\cs{@citex} defined as in \LaTeXe}
+% \changes{5.2}{1994 Aug 25}{Local config file \texttt{natbib.cfg} read in}
+% \changes{5.3}{1994 Sep 13}{Add \cs{citefullauthor}, options \texttt{angle}, 
+%                             \texttt{curly}}
+% \changes{5.3}{1994 Sep 19}{Add star version of \cs{cite} for full authors}
+% \changes{5.3}{1994 Sep 26}{Fix accents in citations with proper definition
+%                             of \cs{protect}}
+% \changes{5.4}{1994 Nov 24}{Add space in \cs{@citex} for text cites}
+% \changes{5.4}{1994 Nov 24}{Replace \cs{if@tempswa} by \cs{ifNAT@swa}}
+% \changes{5.4}{1994 Nov 24}{Add superscript citation type to \cs{bibpunct}}
+% \changes{5.4}{1994 Nov 24}{Add \cs{@citesuper}, fix up bugs in superscripts}
+% \changes{5.4}{1994 Nov 24}{Define \cs{@citexnum} as in \LaTeXe}
+% \changes{5.4}{1995 Feb 03}{Add \cs{citestyle} same as \cs{bibstyle}}
+% \changes{5.4}{1995 Feb 08}{For repeated years and authors, print just letter}
+% \changes{5.5}{1995 Mar 13}{Add \cs{bibhang} and command space in
+%      \cs{@cite}}
+% \changes{5.5}{1995 Mar 16}{Add \cs{citealt} for citation with no
+%      parentheses}
+% \changes{5.5}{1995 Mar 24}{Reorganize internal commands, using \cs{NAT@}
+%     prefixes}
+% \changes{5.5}{1995 Mar 24}{Punctuation selection commands \cs{bibpunct},
+%     \cs{citestyle} are now preamble only, whereas previously they had to
+%     come after the preamble}
+% \changes{5.5}{1995 May 14}{Change names of punctuation commands to
+%     \cs{NAT@...}}
+% \changes{6.0}{1995 Sep 4}{Allow numerical styles with author-year
+%     \texttt{bst} files}
+% \changes{6.0}{1995 Sep 21}{Add automatic indexing of citations}
+% \changes{6.0}{1995 Sep 29}{Accommodate \texttt{index} package}
+% \changes{6.1}{1995 Nov 22}{Fixed for \LaTeXe\ \texttt{1995/12/01}}
+% \changes{6.1}{1995 Dec 4}{Make more robust against changes to internals}
+% \changes{6.1a}{1995 Dec 19}{Fix test for changed citations}
+% \changes{6.2}{1996 Jan 10}{Replace all \cs{uppercase}}
+% \changes{6.2}{1996 Jan 11}{Add \cs{citet}}
+% \changes{6.2}{1996 Feb 2}{Fix superscript size}
+% \changes{6.2}{1996 Mar 05}{Add length \cs{bibsep} for linespacing between
+%               references}
+% \changes{6.2}{1996 Apr 15}{Fix clash with \texttt{amsart} and
+%              \texttt{amsbook}}
+% \changes{6.3}{1996 Jun 10}{Allow \texttt{showkeys} to be loaded first}
+% \changes{6.3}{1996 Jun 17}{Fix punctuation for \texttt{plainnat}}
+% \changes{6.3}{1996 Jun 17}{Suppress extra labels with numericals}
+% \changes{6.4}{1996 Jun 18}{Provide \cs{bibname} and \cs{refname}}
+% \changes{6.4}{1996 Jun 27}{Change \texttt{nlinproc} option to \texttt{egs}}
+% \changes{6.4}{1996 Sep 1}{Make compatible with \texttt{chapterbib.sty}}
+% \changes{6.4}{1996 Sep 12}{Fix spacing for superscripts}
+% \changes{6.4}{1996 Sep 12}{Extra letter printed with \cs{citeyear}}
+% \changes{6.4}{1996 Sep 13}{Add compression and sorting of numerical citations}
+% \changes{6.4}{1996 Oct 2}{Make compatible with \texttt{hyperref.sty}}
+% \changes{6.5}{1996 Dec 11}{KOMA script compatibility}
+% \changes{6.5}{1997 Jan 10}{For EGS, no blank line between references}
+% \changes{6.5}{1997 Jan 30}{Recode notes so they work with \cs{citet} and
+%     \cs{citep}; change documentation to stress these commands over \cs{cite}}
+% \changes{6.5}{1997 Feb 5}{Fix KOMA script properly}
+%
+% \CheckSum{1706}
+% \CharacterTable
+%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
+%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
+%   Digits        \0\1\2\3\4\5\6\7\8\9
+%   Exclamation   \!     Double quote  \"     Hash (number) \#
+%   Dollar        \$     Percent       \%     Ampersand     \&
+%   Acute accent  \'     Left paren    \(     Right paren   \)
+%   Asterisk      \*     Plus          \+     Comma         \,
+%   Minus         \-     Point         \.     Solidus       \/
+%   Colon         \:     Semicolon     \;     Less than     \<
+%   Equals        \=     Greater than  \>     Question mark \?
+%   Commercial at \@     Left bracket  \[     Backslash     \\
+%   Right bracket \]     Circumflex    \^     Underscore    \_
+%   Grave accent  \`     Left brace    \{     Vertical bar  \|
+%   Right brace   \}     Tilde         \~}
+%
+% \iffalse
+%<*install>
+%^^A =============================================
+%^^A    Here is the docstrip installation file
+%^^A    It is written on first LaTeX run
+%^^A =============================================
+\begin{filecontents}{natbib.ins}
+% Simply TeX or LaTeX this file to extract various files from 
+%  the source file `natbib.dtx'
+% Comment out the \generateFile lines for any files you do not want.
+
+\def\batchfile{natbib.ins}
+\input docstrip
+
+\preamble
+
+Only a few abbreviated comments remain here to describe the usage.
+
+\endpreamble
+\postamble
+<<<<< End of decommented file <<<<<<
+\endpostamble
+\keepsilent
+
+\generateFile{natbib.sty}{f}{\from{natbib.dtx}{package,all}}
+
+\preamble
+
+This is the LaTeX 2.09 version of the package.
+It will not be maintained forever.
+Please upgrade to LaTeX2e so that you may use the proper package.
+
+Only a few abbreviated comments remain here to describe the usage.
+
+\endpreamble
+
+% Activate the next line to get a version for running under LaTeX 2.09
+%\generateFile{natbib209.sty}{f}{\from{natbib.dtx}{package,all,209}}
+
+\preamble
+
+This is the driver file to produce the LaTeX documentation from the 
+source file \inFileName.
+Make changes to it as needed. (Never change the \inFileName file!)
+\endpreamble
+\postamble
+
+End of documentation driver file.
+\endpostamble
+
+% Activate the next line for a documentation driver 
+%   that you can configure yourself.
+%\generateFile{natbib.drv}{f}{\from{natbib.dtx}{driver}}
+
+\obeyspaces
+\Msg{*******************************************}%
+\Msg{* For documentation, process natbib.dtx   *}%
+\Msg{*    or the driver file      natbib.drv   *}%
+\Msg{* (LaTeX2e only!)                         *}%
+\Msg{*******************************************}
+\end{filecontents}
+%</install>
+%<*driver>
+\documentclass{ltxdoc}
+%<driver>%\documentclass[twoside]{ltxdoc}
+%<driver>%\documentclass[a4paper]{ltxdoc}
+%<driver>%\documentclass[twoside,a4paper]{ltxdoc}
+\raggedbottom
+
+ %** To include the detailed explanation of the coding, comment out
+ %**   the next line
+\OnlyDescription
+
+ %** To produce a command index: add the following line for one run,
+ %**   then run  makeindex -s gind.ist natbib
+ %**   and reprocess, with or without this line (much faster without)
+%<driver>% \EnableCrossrefs\CodelineIndex 
+
+ %** To produce a change history: add the following line for one run,
+ %**   then run  makeindex -s gglo.ist -o natbib.gls natbib.glo
+ %**   and reprocess, with or without this line (faster without)
+%<driver>% \RecordChanges 
+
+\DisableCrossrefs %May stay; zapped by \EnableCrossrefs
+\CodelineNumbered %May stay
+
+\begin{document}
+   \DocInput{natbib.dtx}
+\end{document}
+%</driver>
+%\fi
+%
+% \DoNotIndex{\begin,\CodelineIndex,\CodelineNumbered,\def,\DisableCrossrefs}
+% \DoNotIndex{\DocInput,\documentclass,\EnableCrossrefs,\end,\GetFileInfo}
+% \DoNotIndex{\NeedsTeXFormat,\OnlyDescription,\RecordChanges,\usepackage}
+% \DoNotIndex{\ProvidesClass,\ProvidesPackage,\ProvidesFile,\RequirePackage}
+% \DoNotIndex{\LoadClass,\PassOptionsToClass,\PassOptionsToPackage}
+% \DoNotIndex{\DeclareOption,\CurrentOption,\ProcessOptions,\ExecuteOptions}
+% \DoNotIndex{\AtEndOfClass,\AtEndOfPackage,\AtBeginDocument,\AtEndDocument}
+% \DoNotIndex{\InputIfFileExists,\IfFileExists,\ClassError,\PackageError}
+% \DoNotIndex{\ClassWarning,\PackageWarning,\ClassWarningNoLine}
+% \DoNotIndex{\PackageWarningNoLine,\ClassInfo,\PackageInfo,\MessageBreak}
+% \DoNotIndex{\space,\protect,\DeclareRobustCommand,\CheckCommand}
+% \DoNotIndex{\newcommand,\renewcommand,\providecommand,\newenvironment}
+% \DoNotIndex{\renewenvironment,\newif,\newlength,\newcounter,\setlength}
+% \DoNotIndex{\setcounter,\if,\ifx,\ifcase,\ifnum,\ifdim,\else,\fi}
+% \DoNotIndex{\texttt,\textbf,\textrm,\textsl,\textsc,\reset@font}
+% \DoNotIndex{\textup,\textit,\textmd,\textsf,\emph,\futurelet}
+% \DoNotIndex{\ttfamily,\rmfamily,\sffamily,\mdseries,\bfseries,\upshape}
+% \DoNotIndex{\slshape,\scshape,\itshape,\em,\LaTeX,\LaTeXe}
+% \DoNotIndex{\filename,\fileversion,\filedate,\let,\makeindex}
+% \DoNotIndex{\@auxout,\@for,\@gobble,\@ifnextchar,\@m,\@mkboth,\@nil}
+% \DoNotIndex{\@noitemerr,\@tempa,\@tempswafalse,\@tempswatrue,\@warning}
+% \DoNotIndex{\advance,\arabic,\AtBeginDocument,\bf,\bibname,\chapter}
+% \DoNotIndex{\citation,\clubpenalty,\CodelineNumbered,\csname}
+% \DoNotIndex{\DisableCrossrefs,\do,\edef,\else,\endcsname,\endlist}
+% \DoNotIndex{\expandafter,\fi,\gdef,\global,\hbox,\hfill,\hskip,\hspace}
+% \DoNotIndex{\if,\if@filesw,\if@tempswa,\ifx,\immediate,\itemindent,\labelsep}
+% \DoNotIndex{\labelwidth,\lastskip,\leftmargin,\list,\mbox,\newblock}
+% \DoNotIndex{\newpage,\p@enumiv,\parindent,\penalty,\refname}
+% \DoNotIndex{\relax,\section,\settowidth,\sfcode,\sloppy,\small,\string}
+% \DoNotIndex{\theenumiv,\thepage,\unskip,\uppercase,\usecounter,\vskip}
+% \DoNotIndex{\widowpenalty,\write,\xdef,\z@,\catcode,\ifnum,\the}
+% \DoNotIndex{\.,\@empty,\@ifundefined,\@latex@warning,\@minus,\@plus,\ }
+% \DoNotIndex{\document,\@namedef,\@listi}
+% \DoNotIndex{\listparindent,\noexpand,\par,\parsep,\pb,\pbf,\pbfseries}
+% \DoNotIndex{\pc,\pd,\pem,\pit,\pitshape,\pmdseries,\prm,\prmfamily,\psc}
+% \DoNotIndex{\pscshape,\psf,\psffamily,\psl,\pslshape,\ptt,\pttfamily}
+% \DoNotIndex{\pupshape,\@iden,\@firstofone,\@unexpandable@protect}
+% \DoNotIndex{\&,\{,\},\bibitem,\bibindent,\if@draft,\typeout}
+% \DoNotIndex{\@ifclassloaded,\@ifstar,\@onlypreamble,\@preamblecmds}
+% \DoNotIndex{\addtolength,\endinput,\@bsphack,\begingroup,\@wrindex}
+% \DoNotIndex{\@listctr,\bibname,\enddocument,\hfil,\ignorespaces,\item}
+% \DoNotIndex{\NAT@temp,\refname,\stepcounter,\@ifpackageloaded}
+% \DoNotIndex{\@gobbletwo,\index,\itemsep,\markright,\scriptsize}
+% \DoNotIndex{\textsuperscript}
+%
+% \setcounter{IndexColumns}{2}
+% \setlength{\IndexMin}{10cm}
+% \setcounter{StandardModuleDepth}{1}
+%
+% \hyphenation{par-en-the-ti-cal}
+%
+% \GetFileInfo{natbib}
+%
+% \title{{\bfseries Natural Sciences Citations and References}\\
+%         (Author--Year and Numerical Schemes)}
+%    
+% \author{Patrick W. Daly}
+%         
+% \date{This paper describes package \texttt{\filename}\\
+%       version \fileversion{} from \filedate\\[1ex]
+%^^A     \textsl{It is part of the \texttt{preprint} collection of packages}\\
+%     \textbf{It is intended for \LaTeXe}
+%     \\ (but does include a variant for \LaTeX~2.09)
+%  }
+% 
+% \maketitle
+%
+% \pagestyle{myheadings}
+% \markboth{P. W. Daly}{NATURAL SCIENCES CITATIONS AND REFERENCES}
+%
+% \newcommand{\btx}{\textsc{Bib}\TeX}
+% \newcommand{\thestyle}{\texttt{\filename}}
+%
+%^^A In order to keep all marginal notes on the one (left) side:
+%^^A (otherwise they switch sides disasterously with twoside option)
+% \makeatletter \@mparswitchfalse \makeatother 
+%
+% \begin{abstract}
+% Journals in the natural sciences tend to use the author--year style of
+% literature citations, in contrast to the numerical style supported by
+% \LaTeX{} and \btx. A number of contributed packages exist to accommodate this
+% citation mode, but each one is tailored to a limited number of \btx\ style
+% (\texttt{.bst} files. The reason is that each one reads in the author--year
+% information in different formats for the |\bibitem| commands.
+% In contrast, 
+% the \thestyle{} package supports not only the various author--year
+% bibliography styles, but also those for standard numerical citations. In
+% fact, it can also produce numerical citations even with an author--year
+% bibliographic style, something that permits easy switching between the
+% two citation modes. To this end, replacements for the standard
+% \LaTeX\ \texttt{.bst} files are also provided.
+% 
+% It is possible to define the citation \emph{style} (type of brackets and
+% punctuation between citations) and even to associate it with the name of the
+% bibliographic style so that it is automatically activated. Citation styles
+% can be defined for local \texttt{.bst} files by means of a configuration file
+% \thestyle\texttt{.cfg}.
+%  
+% It is compatible with the packages: \texttt{index}, \texttt{showkeys}, 
+% \texttt{chapterbib}, \texttt{hyperref},
+% and with the classes \texttt{amsbook} and
+% \texttt{amsart}. It can also emulate the sorting and compressing
+% functions of the \texttt{cite} package (with which it is otherwise
+% incompatible).
+%
+% The \thestyle\ package therefore acts as a single, flexible interface for 
+% most of the available bibliographic styles.
+%
+% \end{abstract}  
+% 
+% \section{Introduction}
+% The first problem of using author--year literature citations with standard
+% \LaTeX{} is that the two forms of citations are not supported. These are:
+% \begin{quote}
+% textual: \dots\ as shown by Jones et al. (1990) \dots\\
+% parenthetical: It has been shown (Jones et al., 1990) that \dots
+% \end{quote}
+% There is only one |\cite| command to do both jobs.
+% 
+% A second problem is that the \texttt{thebibliography} environment for
+% listing the references insists on including the {\em labels\/} in the
+% list. These labels are normally the numbers, needed for referencing. In
+% the author--year system, they are superfluous and should be left off.
+% Thus, if one were to make up a bibliography with the author--year as
+% label, as
+% \begin{quote}
+% \begin{verbatim}
+% \begin{thebibliography}{...}
+% \bibitem[Jones et al., 1990]{jon90}
+% Jones, P. K., . . .
+% \end{thebibliography}
+% \end{verbatim}
+% \end{quote}
+% then |\cite{jon90}| produces the parenthetical citation [Jones et al.,
+% 1990], but there is no way to get the textual citation. Furthermore,
+% the citation text will also be included in the list of references. 
+% 
+% The final problem is to find a \btx{} bibliography style that will be
+% suitable.
+% 
+% \section{Previous Solutions}
+% \begin{quote}\slshape
+% This section may not be of interest to all users. To find out how to use
+% \thestyle\ without reading about the historical background, go to
+% Section~\ref{sec:usage}.
+% \end{quote}
+% 
+% Although the author--year citation mode is not supported by
+% \emph{standard} \LaTeX, there are a number of contributed packages that
+% try to solve this problem. The various bibliographic styles
+% (\texttt{.bst} files) that exist are usually tailored to be used with a
+% particular \LaTeX{} package.
+% 
+% I have found a large number of \texttt{.bst} files on file servers that may
+% act as indicators of the various systems available.
+% 
+% \subsection{The \texttt{natsci.bst} Style}
+% What gave me my first inspiration was Stephen Gildea's \texttt{natsci.bst}
+% for use with his \texttt{agujgr.sty} file. This showed me that the problem
+% was solvable. However, Gildea's style formats |\bibitem| just as I
+% illustrated above: with an optional label consisting of abbreviated
+% authors and year. Thus only parenthetical citations can be accommodated.
+% The list of references, however, is fixed up in his style files.
+% 
+% \subsection{The \texttt{apalike.bst} Style}
+% Oren Patashnik, the originator of \btx{} and the standard \texttt{.bst}
+% files, has also worked on an author--year style, called \texttt{apalike.bst}
+% with a corresponding \texttt{apalike.sty} to support it. Again, only the
+% parenthetical citation is provided. Except for the fact that his style
+% works with version~0.99 of \btx, its functionality is identical to that
+% of the \texttt{natsci} files.
+% 
+% Patashnik does not like author--year citations. He makes this very clear
+% in his \btx{} manuals and in the header to \texttt{apalike.bst}.
+% Nevertheless, one should respect his work in this area, simply because he
+% should be the best expert on matters of \btx. Thus \texttt{apalike.bst}
+% could be the basis for other styles.
+% 
+% The form of the \texttt{thebibliography} entries in this system is
+% \begin{quote}
+% |\bibitem[Jones et al., 1990]{jon90}...|
+% \end{quote}
+% the same as I illustrated earlier. This is the most minimal form that can
+% be given. I name it the \texttt{apalike} variant, after Patashnik's 
+% \texttt{apalike.bst} and \texttt{apalike.sty}. However, there could be many
+% independent \texttt{.bst} files that follow this line.
+% 
+% The bibliography style files belonging to this group include:
+% \begin{quote}
+% \texttt{apalike}, \texttt{apalike2}, \texttt{cea}, \texttt{cell}, 
+% \texttt{jmb}, \texttt{phapalik}, \texttt{phppcf}, \texttt{phrmp}
+% \end{quote}
+% 
+% \subsection{The \texttt{newapa} Style}
+% A major improvement has been achieved with \texttt{newapa.bst} and the
+% accompanying \texttt{newapa.sty} files by Stephen N. Spencer and Young U.
+% Ryu. Under their system, three separate items of information are included
+% in the |\bibitem| label, to be used as required. These are: the full
+% author list, the abbreviated list, and the year. This is accomplished by
+% means of a |\citeauthoryear| command included in the label, as
+% \begin{quote}
+% |\bibitem[\protect\citeauthoryear{Jones, Barker,|\\
+% |  and Williams}{Jones et al.}{1990}]{jon90}...|
+% \end{quote}
+% Actually, this only illustrates the basic structure of |\citeauthoryear|;
+% the \texttt{newapa} files go even further to replace some words and 
+% punctuation
+% with commands. For example, the word `and' above is really
+% |\betweenauthors|, something that must be defined in the \texttt{.sty} file.
+% Of course, |\citeauthoryear| is also defined in that file. A
+% number of different |\cite| commands are available to print out the
+% citation with complete author list, with the short list, with or without
+% the date, the textual or parenthetical form. 
+% 
+% Thus the |\citeauthoryear| entry in |\bibitem| is very flexible,
+% permitting the style file to generate every citation form that one might
+% want. It is used by a number of other styles, with corresponding
+% \texttt{.sty} files. They all appear to have been inspired by 
+% \texttt{newapa.bst}, although they lack the extra punctuation commands. 
+% 
+% Bibliographic style files belonging to the \texttt{newapa} group include
+% \begin{quote}
+% \texttt{newapa}, \texttt{chicago}, \texttt{chicagoa}, \texttt{jas99}, 
+% \texttt{named}
+% \end{quote}
+% Note: the last of these, \texttt{named.bst}, uses |\citeauthoryear| in a
+% slightly different manner, with only two arguments: the short list and
+% year.
+% 
+% \subsection{The Harvard Family}
+% The same effect is achieved by a different approach in the Harvard family
+% of bibliographic styles. Here a substitute for |\bibitem| is used, as
+% \begin{quote}
+% |\harvarditem[Jones et al.]{Jones, Baker, and|\\
+% |   Williams}{1990}{jon90}...|
+% \end{quote}
+% The accompanying interface package file is called \texttt{harvard.sty}
+% and is written by Peter Williams and Thorsten Schnier. It
+% defines |\harvarditem| as well as the citation commands |\cite|, for
+% parenthentical, and |\citeasnoun|, for textual citations. The first
+% citation uses the long author list, following ones the shorter list, if
+% it has been given in the optional argument to |\harvarditem|.
+% 
+% Bibliography styles belonging to the Harvard family are
+% \begin{quote}
+% \texttt{agsm}, \texttt{dcu}, \texttt{kluwer}
+% \end{quote}
+% 
+% This package has been updated for \LaTeXe, with many additions to
+% add flexibility. The result is a powerful interface that should meet most
+% citation needs. (It does not suppress repeated authors, though,
+% as \thestyle{} does.)
+%
+% \subsection{The Astronomy Style}
+% Apparently realizing the limitations of his \texttt{apalike} system, Oren
+% Patashnik went on to develop a `true' \texttt{apa} bibliographic style,
+% making use of the method already employed by an astronomy journal. This
+% is actually very similar to the \texttt{newapa} label but with only the
+% short list of authors:
+% \begin{quote}
+% |\bibitem[\protect\astroncite{Jones et al.}{1990}]{jon90}|\\
+% |   ...|
+% \end{quote}
+% It requires the package file \texttt{astron.sty} 
+% or any other style that defines |\astroncite| appropriately.
+% 
+% Bibliographic styles belonging to the astronomy group are
+% \begin{quote}
+% \texttt{apa}, \texttt{astron}, \texttt{bbs}, \texttt{cbe}, 
+% \texttt{humanbio}, \texttt{humannat}, \texttt{jtb}
+% \end{quote}
+% 
+% This is as good as the |\citeauthoryear| command, although not as
+% flexible since the full list of authors is missing.
+% 
+% \subsection{The \texttt{authordate} Style}
+% Finally, I have also found some packages making use of a label command
+% called |\citename| in the form
+% \begin{quote}
+% |\bibitem[\protect\citename{Jones et al., }1990]{jon90}|\\
+% |    ...|
+% \end{quote}
+% 
+% This is not a good system since the author list and date are not cleanly
+% separated as individual arguments, and since the punctuation is included
+% in the label text. It is better to keep the punctuation fully removed, as
+% part of the definitions in the \texttt{.sty} file, for complete flexibility.
+% 
+% Bibliographic styles belonging to this group are
+% \begin{quote}
+% \texttt{authordate1}, \texttt{authordate2}, \texttt{authordate3}, 
+% \texttt{authordate4}, \texttt{aaai-named}
+% \end{quote}
+% with accompanying style file \texttt{authordate1-4.sty}.
+% 
+% \section{The \thestyle{} System}
+% The form of the |\bibitem| entry that I have used for all my
+% bibliographic styles is only slightly more complicated than the minimal
+% one, but allows a clean separation between authors and date:
+% \begin{quote}
+% |\bibitem[Jones et al.(1990)]{jon90}...|\\[1ex]
+% or alternatively\\[1ex]
+% |\bibitem[Jones et al.(1990)Jones, Baker, |\\
+% \hspace*{2em}|and Williams]{jon90}...|
+% \end{quote}
+%
+% (One weakness of the \thestyle{} format is that it fails if the author
+% list itself contains parentheses! This may be fixed up if the author list
+% is grouped in curly braces.)
+% 
+% I wanted to name the system something like `natural sciences bibliography',
+% intending it to be a variant of \texttt{natsci.sty}. Since that name
+% was already taken, I resorted to the rather cryptic, and definitely ugly,
+% \thestyle.
+% 
+% The \thestyle\texttt{.sty} package\footnote{Formerly called a \emph{style 
+% file} in the older \LaTeX~2.09 terminology.}
+% supports not only my own |\bibitem| format, but
+% also all the others described here, plus numerical citation modes.
+% The additional questions of citation style (type of brackets, commas or
+% semi-colons between citations) can be defined once and for all for each
+% \texttt{.bst} file and need never be specified explicitly in the source text.
+% The use of |\cite| is the same for all citation styles, meaning that the
+% additional features that might be available in the `proper' \texttt{.sty}
+% file will be missing. (This could be changed later.) The result is a
+% single \LaTeX{} package to handle {\em all\/} the bibliographic
+% styles in a uniform manner.
+% 
+% As of version 5.1 (1994 June 22), the source file contains coding for a
+% \LaTeXe{} package file (the new standard) as well as that for an older
+% \LaTeX~2.09 style option file. The latter is extracted with the
+% \texttt{docstrip} option \texttt{209}. 
+% 
+% \begin{quote}\slshape
+% \textbf{New to version 6.0}: (1995 Sep 29) \\
+% In previous versions, each \texttt{.bst} file was either numerical or
+% author--year only. Applying the wrong mode led to grotesque results, and
+% the mode could not always be selected automatically. With version~6.0,
+% all the author--year bibliographic style files can also be used for
+% \emph{numerical} citations, by simply selecting the mode in one of the
+% ways described in Sections~\ref{sec:bibpunct} and \ref{sec:opts}. It is
+% not possible to employ author-year citations with pure numerical
+% \texttt{.bst} files, and never will be. 
+% 
+% See Section~\ref{sec:6.0} for more information.
+% \end{quote}
+% 
+% \section{Using this Package}\label{sec:usage}
+% 
+% In this paper, I distinguish between the citation \emph{mode} (author--year
+% or numerical) and citation \emph{style} (the type of punctuation used for
+% citations). The citation style is something that is independent of the
+% bibliography style and is not programmed in the \texttt{.bst} files.
+% 
+% \subsection{Basic Citation Commands}
+% 
+% \DescribeMacro{\citet}
+% \DescribeMacro{\citep}
+% The \thestyle{} package has two basic citation commands, |\citet| and
+% |\citep| for \emph{textual} and \emph{parenthetical} citations, respectively.
+% There also exist the starred versions |\citet*| and |\citep*| that print
+% the full author list, and not just the abbreviated one.
+% All of these may take one or two optional arguments to add some text before
+% and after the citation.
+% \begin{quote}
+% \begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+%   |\citet{jon90}| & Jones et al. (1990)\\
+%   |\citet[chap.~2]{jon90}| & Jones et al. (1990, chap.~2)\\[0.5ex]
+%   |\citep{jon90}| & (Jones et al., 1990)\\
+%   |\citep[chap.~2]{jon90}| & (Jones et al., 1990, chap.~2)\\
+%   |\citep[see][]{jon90}| & (see Jones et al., 1990)\\
+%   |\citep[see][chap.~2]{jon90}| & (see Jones et al., 1990, chap.~2)\\[0.5ex]
+%   |\citet*{jon90}| & Jones, Baker, and Williams (1990)\\
+%   |\citep*{jon90}| & (Jones, Baker, and Williams, 1990)
+% \end{tabular}
+% \end{quote}
+% The starred versions can only list the full authors if the \texttt{.bst}
+% file supports this feature; otherwise, the abbreviated list is printed.
+%
+% In standard \LaTeX, the |\cite| command can only take a single optional
+% text for a note after the citation; here, a single optional text is a
+% post-note, while two are the pre- and post-note. To have only a pre-note, it
+% is necessary to provide an empty post-note text, as shown above.
+% 
+% Multiple citations may be made as usual, by including more than one
+% citation key in the |\cite| command argument. \textsl{If adjacent citations
+% have the same author designation but different years, then the author
+% names are not reprinted.}
+% \begin{quote}
+% \begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+%   |\citet{jon90,jam91}| & Jones et al. (1990); James et al. (1991)\\
+%   |\citep{jon90,jam91}| & (Jones et al., 1990; James et al. 1991)\\
+%   |\citep{jon90,jon91}| & (Jones et al., 1990, 1991)\\
+%   |\citep{jon90a,jon90b}| & (Jones et al., 1990a,b)
+% \end{tabular}
+% \end{quote}
+%
+% These examples are for author--year citation mode. In numerical mode, the 
+% results are different.
+% \begin{quote}
+% \begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+%   |\citet{jon90}| & Jones et al. [21]\\
+%   |\citet[chap.~2]{jon90}| & Jones et al. [21, chap.~2]\\[0.5ex]
+%   |\citep{jon90}| & [21]\\
+%   |\citep[chap.~2]{jon90}| & [21, chap.~2]\\
+%   |\citep[see][]{jon90}| & [see 21, 1990]\\
+%   |\citep[see][chap.~2]{jon90}| & [see 21, chap.~2]\\[0.5ex]
+%   |\citep{jon90a,jon90b}| & [21, 32]
+% \end{tabular}
+% \end{quote}
+% The authors can only be listed if the \texttt{.bst} file supports
+% author--year citations. The standard \texttt{.bst} files, such as
+% \texttt{plain.bst} are numerical only and transfer no author--year
+% information to \LaTeX. In this case, |\citet| prints ``\textbf{(author?)} 
+% [21].''
+% 
+% {\slshape Do not use multiple citations with the |\citet| command in
+% numerical mode!}
+% 
+% \DescribeMacro{\cite}
+% In the original versions of \thestyle, the traditional |\cite| command was
+% used for both textual and parenthetical citations. The presence of an empty
+% optional text in square brackets signaled parenthetical. This syntax has been
+% retained for compatibility, but is no longer encouraged.
+% 
+% This means that |\cite| (without notes) is the same as |\citet| in
+% author--year mode, whereas in numerical mode, it is the same as |\citep|.
+% The starred version, as well as the one or two optional notes, may also be
+% used.
+%
+% \subsection{Extended Citation Commands}
+% 
+% \DescribeMacro{\citealt}
+% As an alternative form of citation, |\citealt| is the same as |\citet|
+% but \emph{without any parentheses}. Multiple references and the
+% starred variant also exist.
+% \begin{quote}
+% \begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+%   |\citealt{jon90}| & Jones et al. 1990\\
+%   |\citealt*{jon90}| & Jones, Baker, and Williams 1990\\
+%   |\citealt{jon90,jam91}| & Jones et al. 1990; James et al. 1991
+% \end{tabular}
+% \end{quote}
+%
+% \DescribeMacro{\citeauthor}
+% \DescribeMacro{\citeyear}
+% \DescribeMacro{\citefullauthor}
+% In author--year schemes, it is sometimes desirable to be able to refer to
+% the authors without the year, or vice versa. This is provided with three
+% extra commands
+% \begin{quote}
+% \begin{tabular}{l@{\quad$\Rightarrow$\quad}l}
+%   |\citeauthor{jon90}| & Jones et al.\\
+%   |\citefullauthor{jon90}| & Jones, Baker, and Williams\\
+%   |\citeyear{jon90}|   & 1990
+% \end{tabular}
+% \end{quote}
+% If the full author information is missing, then |\citefullauthor| is
+% the same as |\citeauthor|, printing only the abbreviated list.
+% This also applies to the starred versions of |\citet| and |\citep|.
+% 
+% If the author or year information is missing (as is the case with the
+% standard \LaTeX{} \texttt{.bst} files), these commands issue a warning.
+% 
+% As of version~6.0, these commands may also be used with numerical
+% citations, provided an author--year \texttt{.bst} file is being employed.
+% 
+% The native \thestyle{} form of the |\bibitem| entry now 
+% also supports the full author list.
+%
+% \textsl{Multiple citations are \emph{not} allowed with these commands.}
+% 
+% \subsection{Selecting Citation Punctuation}\label{sec:bibpunct}
+%
+% \DescribeMacro{\bibpunct}
+% The above examples have been printed with the default citation style.
+% It is possible to change this, as well as to select numerical or
+% author--year mode, by means of the |\bibpunct| command, which takes 
+% one optional and 6 mandatory arguments. The mandatory ones are:
+% \begin{enumerate}
+% \item the opening bracket symbol, default = (
+% \item the closing bracket symbol, default = )
+% \item the punctuation between multiple citations, default = ;
+% \item the letter `n' for numerical style, or `s' for numerical superscript
+%       style, any other letter for
+%       author--year, default = author--year; note, it is not necessary to
+%       specify which author--year interface is being used, for all will be
+%       recognized;
+% \item the punctuation that comes between the author names and the year
+%       (parenthetical case only), default = ,
+% \item the punctuation that comes between years when common author lists
+%       are suppressed (default = ,); if both authors and years are common,
+%       the citation is printed as `1994a,b', but if a space is wanted between
+%       the extra letters, then include the space in the argument, as |{,~}|.
+% \end{enumerate}
+% 
+% The optional argument is the character preceding a post-note, default is a
+% comma.
+%
+% The |\bibpunct| command must be issued in the preamble, that is,
+% before |\begin{document}|. (\textbf{Note:} in versions 5.4 or earlier, this
+% declaration had to be given after the preamble!)
+% 
+% Example~1, |\bibpunct{[}{]}{,}{a}{}{;}| changes the output of
+% \begin{quote}
+%   |\citep{jon90,jon91,jam92}| 
+% \end{quote}
+% into [Jones et al. 1990; 1991, James et al. 1992].
+%
+% Example~2, |\bibpunct[;]{(}{)}{,}{a}{}{;}| changes the output of
+% \begin{quote}
+%   |\citep[and references therein]{jon90}| 
+% \end{quote}
+% into (Jones et al. 1990; and references therein).
+% 
+% \DescribeMacro{\bibstyle@xxx}
+% Usually the citation style is determined by the journal
+% for which one is writing, and is as much a part of the bibliography style
+% as everything else. The \thestyle{} package allows
+% punctuation definitions to be directly coupled to the
+% |\bibliographystyle| command that must always be present when \btx{} is
+% used. It is this command that selects the \texttt{.bst} file; by adding such
+% a coupling to \thestyle{} for every \texttt{.bst} file that one might
+% want to use, it is not necessary to add |\bibpunct| explicitly in the
+% document itself, unless of course one wishes to override the preset
+% values.
+% 
+% Such a coupling is achieved by defining a command |\bibstyle@|{\em bst},
+% where {\em bst\/} stands for the name of the \texttt{.bst} file. For example,
+% the American Geophysical Union (AGU) demands in its publications that
+% citations be made with square brackets and separated by semi-colons. I
+% have an \texttt{agu.bst} file to accomplish most of the formatting, but such
+% punctuations are not included in it. Instead, \thestyle{} has the
+% definition
+% \begin{quote}
+% |\newcommand{\bibstyle@agu}{\bibpunct{[}{]}{;}{a}{,}{,~}}|
+% \end{quote}
+% 
+% These style defining commands may contain more than just |\bibpunct|.
+% Some numerical citation scheme require even more changes. For example,
+% the journal \textsl{Nature} not only uses superscripted numbers for 
+% citations, it also prints the numbers in the list of references without
+% the normal square brackets. To
+% accommodate this, \thestyle{} contains the style definition
+% \begin{quote}\begin{verbatim}
+% \newcommand{\bibstyle@nature}{\bibpunct{}{}{,}{s}{}{}%
+%      \gdef\NAT@biblabelnum##1{##1.}}
+% \end{verbatim}
+% \end{quote}
+% The redefined |\NAT@biblabelnum| command specifies how the reference numbers
+% are to be formatted in the list of references itself.
+% The redefinition must be made with |\gdef|, not |\def| or
+% |\renewcommand|.
+% 
+% The selected punctuation style and other redefinitions will not be in
+% effect on the first \LaTeX{} run, for they are stored to the auxiliary
+% file for the subsequent run.
+% 
+% The user may add more such definitions of his own, to accommodate those
+% journals and \texttt{.bst} files that he has. He may either add them to
+% his local copy of \thestyle\texttt{.sty}, or better put them into a file
+% named \thestyle\texttt{.cfg}. This file will be read in if it exists,
+% adding any local configurations. Thus such configurations can survive
+% future updates of the package. (This is for \LaTeXe{} only.)
+% 
+% \medskip
+% \noindent\textbf{Note:} 
+% with version~6.0, any explicit call to |\bibpunct| has priority over the 
+% predefined citation styles.
+% 
+% \DescribeMacro{\citestyle}
+% A preprogrammed citation style is normally invoked by the command
+% |\bibliographystyle|, as described above. However, it may be that
+% one wants to apply a certain citation style to another bibliography
+% style. This may be done with |\citestyle|, given \emph{before}
+% |\begin{document}|. For example, to use the
+% \texttt{plain} bibliography style (for the list of references) with the
+% \textsl{Nature} style of citations (superscripts),
+% \begin{quote}
+% |\documentclass{article}|\\
+% |\usepackage{|\thestyle|}|\\
+% |. . . . .|\\
+% |\citestyle{nature}|\\
+% |\begin{document}|\\
+% |\bibliographystyle{plain}|\\
+% |. . . . .|
+% \end{quote}
+% 
+% \noindent
+% \textbf{Note:} for versions 5.5 and later, all changes to the citation
+% style, including punctuation, must be made before |\begin{document}|,
+% which freezes the citation style.
+%
+% \subsection{Priority of Style Commands}\label{sec:priority}
+% The citation style (punctuation and mode) can be selected by means of the
+% |\bibpunct|, |\citestyle|, and predefined |\bibstyle@|\textit{bst}
+% commands. They can also be selected by \LaTeXe{} options
+% (Section~\ref{sec:opts}). What happens if there are several conflicting
+% selections?
+% 
+% The lowest priority is assigned to the predefined |\bibstyle@|\textit{bst}
+% commands, since they are implicit and not obvious to the user. The
+% \LaTeXe{} options have the next priority. Finally, any selection by
+% |\bibpunct| and/or |\citestyle| overrides those of the other methods.
+% 
+% \subsection{Other Formatting Options}
+% 
+% \DescribeMacro{\bibsection}
+% The list of references normally appears as a |\section*| or |\chapter*|,
+% depending on the main class. If one wants to redesign one's own heading,
+% say as a numbered section with |\section|, then |\bibsection| may be
+% redefined by the user accordingly.
+% 
+% \DescribeMacro{\bibfont}
+% The list of references is normally printed in the same font size and
+% style as the main body. However, it is possible to define |\bibfont|
+% to be font commands that are in effect within the \texttt{thebibliography}
+% environment.
+%
+% \DescribeMacro{\bibhang}
+% The list of references for author--year styles uses a hanging indentation
+% format: the first line of each reference is flush left, the following lines
+% are set with an indentation from the left margin. This indentation is 1~em
+% by default but may be changed by redefining (with |\setlength|) the 
+% length parameter |\bibhang|.
+%
+% \DescribeMacro{\bibsep}
+% The vertical spacing between references in the list, whether author--year
+% or numerical, is controlled by the length |\bibsep|. If this is set to
+% 0~pt, there is no extra line spacing between references. The default
+% spacing depends on the font size selected in |\documentclass|, and is
+% almost a full blank line. Change this by redefining |\bibsep| with
+% |\setlength| command.
+% 
+% \subsection{Automatic Indexing of Citations}
+% 
+% (New to version 6.0; applies to \LaTeXe\ only)\\[1ex]
+% \DescribeMacro{\citeindextrue}
+% \DescribeMacro{\citeindexfalse}
+% If one wishes to have the citations entered in the \texttt{.idx} indexing
+% file, it is only necessary to issue |\citeindextrue| at any point in the
+% document. All following |\cite| commands, of all variations, then insert
+% the corresponding entry to that file. With |\citeindexfalse|, these
+% entries will no longer be made.
+% 
+% The |\bibitem| commands in the \texttt{thebibliography} environment will
+% also make index entries. If this is not desired, then issue
+% |\citeindexfalse| before |\bibliography| or |\begin{thebibliography}|.
+% 
+% Of course, |\makeindex| must also be issued in the preamble to activate
+% indexing, as usual. Otherwise, no indexing is done at all.
+% 
+% Make sure that the document has been processed at least twice after the
+% last \btx\ run before running the \texttt{makeindex} program.
+% 
+% \DescribeMacro{\NAT@idxtxt}
+% The form of the index entries is set by the internal |\NAT@idxtxt|, which
+% can be redefined by hackers if wanted (in the \thestyle\texttt{.cfg} file
+% please). By default, it prints the short author list plus date in the
+% current parenthesis style.
+% 
+% The \thestyle\ package can also be used with the \texttt{index} package of
+% David~M. Jones. The order in which the packages are loaded is not
+% important. 
+% 
+% \DescribeMacro{\citeindextype}
+% In that package, multiple index lists may be made by means of a |\newindex|
+% command. For example, it may be desirable to put all the citation indexing
+% into a separate list. First that list must be initiated with, e.g.,
+% \begin{quote}
+%    |\newindex{cite}{ctx}{cnd}{List of Citations}|
+% \end{quote}
+% and then the automatic citation indexing associated with this list with the
+% \thestyle\ command
+% \begin{quote}
+%    |\renewcommand{\citeindextype}{cite}|
+% \end{quote}
+% See the documentation for \texttt{index.sty} for details.
+% 
+% \subsection{Hyper\TeX\ Compatibility}
+% As of version~6.4, \thestyle\ is compatible with the \texttt{hyperref} 
+% package of Sebastian Rahtz and Yannis Haralambous, for use with
+% Hyper\TeX. The compatibility is of a mutual nature: both packages contain
+% coding that interact with that of the other. Thus the version of
+% \texttt{hyperref} must be more recent than 1996 Oct~8.
+% ^^A Update the date when it is better known, after checking with Rahtz.
+%
+% \subsection{Multiple Bibliographies in One Document}\label{sec:chapbib}
+% 
+% As of version 6.4, \thestyle\ is compatible with the \texttt{chapterbib}
+% package of Donald Arseneau and Niel Kempson,\relax
+% \footnote{I have used version 1.5 from 1995/10/09; cannot guarantee 
+% earlier versions.}
+% which makes it possible to have several
+% bibliographies in one document. The usual application is to have
+% bibliographies in each chapter of a book, especially if they have been
+% written by different authors.
+% 
+% The \texttt{chapterbib} package works in a very natural way for the
+% author; only the editor who puts all the chapters together into one book
+% has to do some extra work. 
+% 
+% The package makes use of the |\include| command, and it is in fact every
+% |\include|d file that has its own bibliography. For large books, it makes
+% very good sense to take advantage of this feature in any case.
+% 
+% To review the use of |\include|, recall that the main file
+% \begin{verbatim}
+%   \documentclass{...}
+%   \includeonly{ch2}
+%   \begin{document}
+%     \include{ch1}
+%     \include{ch2}
+%     \include{ch3}
+%   \end{document}
+% \end{verbatim}
+% will process only the file \texttt{ch2.tex} as though the files
+% \texttt{ch1.tex} and \texttt{ch3.tex} were also present. That is, all
+% counters, especially the page and section numbers, as well as
+% cross-referencing definitions, will function as if the whole document
+% were processed. The trick is that each |\include|d file has it own
+% \texttt{.aux} file containing these definitions, and they are all read
+% in every time, even if the corresponding \texttt{.tex} file is not. The
+% \texttt{.aux} files also contain the citation information for \btx,
+% something that the \texttt{chapterbib} package exploits.
+% 
+% If |\usepackage{chapterbib}| has been given, the keys in each |\cite|
+% and |\bibitem| command are associated with the current |\include|d file
+% and are distinguished from the identical key in a different file. Each of
+% these files must contain its own |\bibliography| and |\bibliographystyle|
+% commands. One processes \btx\ on each file separately before processing
+% it under \LaTeX\ (at least twice).
+% 
+% \subsubsection{Special Considerations for \thestyle\ and
+%           \texttt{chapterbib}}
+% 
+% The order in which the \texttt{chapterbib} and \thestyle\ packages are loaded
+% is unimportant.
+% 
+% The \texttt{chapterbib} package provides an option \texttt{sectionbib}
+% that puts the bibliography in a |\section*| instead of |\chapter*|,
+% something that makes sense if there is a bibliography in each chapter.
+% This option will not work when \thestyle\ is also loaded; instead, add
+% the option to \thestyle. (The \texttt{sectionbib} option can always be
+% given, but it only has meaning for the \texttt{book} and \texttt{report}
+% classes, or for classes derived from them.)
+% 
+% Every |\include|d file (with citations) must contain its own
+% |\bibliography| command where the bibliography is to appear. The database
+% files listed as arguments to this command can be different in each file,
+% of course. However, what is not so obvious, is that each file must also
+% contain a |\bibliographystyle| command, \emph{preferably with the same
+% style  argument}. If different bibliography styles are specified for
+% different files, then the preprogrammed citation style (punctuation and
+% citation mode) will be that of the first bibliography style given. The
+% preprogrammed citation styles can only be changed in the preamble (see
+% Section~\ref{sec:priority}), something that guarantees a uniform style
+% for the entire document.\relax
+%   \footnote{It would be relatively easy to allow changes in style anywhere
+%   in the document, but this strikes me as bad policy. However, it is
+%   provided for with the \texttt{docstrip} option \texttt{nopreonly}.}
+% 
+% \subsection{Sorting and Compressing Numerical Citations}
+% 
+% Another package by Donald Arseneau, \texttt{cite.sty}, reimplements the
+% entire (numerical) citation system such that one can control the
+% punctuation and citation format, all of which is done by \thestyle\ as
+% well. However, it also can sort and compress numerical citations,
+% something that is required by some journals. 
+% 
+% What this means is that when multiple citations are given with a single
+% |\cite| command, the normal order of the numbers is in the sequence
+% given. This is usually a wild list of numbers, such as [4,2,8,3]. With
+% the \texttt{cite} package, this list becomes [2--4,8].
+% 
+% It is impossible to make the \texttt{cite} and \thestyle\ packages
+% compatible, since both reimplement |\cite| from scratch. Instead, I have
+% taken the necessary coding from \texttt{cite.sty} and modified it for
+% \thestyle{}. This coding becomes activated 
+% by including the option \texttt{sort} in the |\usepackage| command.
+% It only affects numerical
+% citations, and has no influence on the author--year ones.
+% 
+% \section{Numerical Citations with Author--Year Styles}\label{sec:6.0}
+% 
+% (New to version 6.0)\\[1ex]
+% In earlier versions, each \texttt{.bst} file could be used either for
+% numerical or author--year citation mode, without any possibility of
+% switching. Obviously numerical \texttt{.bst} files can never be used for
+% author--year citations (the information is missing in the auxiliary file)
+% but there is no reason why the converse should not work. 
+% 
+% I have been frequently asked if I could implement this feature, and I at
+% first replied that it would be quite easy. That was a mistake. The
+% numerical information was missing in the auxiliary files, so the
+% |\cite| commands could never access it.
+% 
+% \subsection{New Coding}
+% I have now recoded \thestyle{} so that the separation of author and year
+% information comes before the information is written to the auxiliary
+% file, and furthermore, a sequential number is also written. This permits
+% numerical citations with \emph{any} of the author--year bibliographic style
+% files.
+% 
+% The recoding has made fewer internal changes than I expected. Any users
+% who have local redefinitions of my internals should be aware that of the
+% citation commands, only |\NAT@citexnum| has been altered. Otherwise the
+% changes are in the parsing commands |\NAT@parse| and |\NAT@parse@date|.
+% Of the external commands, |\bibitem| is completely redefined, and
+% |\citeauthor|, |\citeyear|, and |\citefullauthor| are different.
+% 
+% Version~5.5 actually made far more internal changes: all internal
+% commands were renamed to conform to recommended \LaTeX{} coding
+% practices.
+% 
+% \subsection{Selecting Numerical Mode}
+% By default, \thestyle{} is in author--year mode. This can be changed by
+% \begin{enumerate}
+%   \item selecting a numerical bibliography style with predefined
+%         citation style, defined either in the package or in the local
+%         configuration file;
+%         
+%   \item giving options \texttt{numbers} or \texttt{super} to the
+%         |\usepackage| command;
+% 
+%   \item issuing |\bibpunct| with the 4th mandatory argument set to \texttt{n}
+%         or \texttt{s};
+% 
+%   \item issuing |\citestyle| with the name of a predefined numerical
+%         bibliography style.
+% \end{enumerate}
+% The methods are listed in order of increasing priority. 
+% 
+% The \thestyle{} package will automatically switch to numerical mode if
+% any one of the |\bibitem| entries fails to conform to the possible
+% author--year formats. There is no way to override this, since such an
+% entry would cause trouble in the author--year mode.
+% 
+% There are certain special `numerical' styles, like that of the standard
+% \texttt{alpha.bst}, which include a non-numerical label in place of the
+% number, in the form
+% \begin{quote} |\bibitem[ABC95]{able95}| \end{quote}
+% As far as \thestyle\ is concerned, this label does not conform to the
+% author--year possibilities and is therefore considered to be numerical.
+% The citation mode switches to numerical, and |\cite{able95}| prints
+% [ABC95].
+% 
+% \subsection{New Bibliography Styles}
+% I provided three new \texttt{.bst} files to replace the standard \LaTeX\
+% numerical ones:
+% \begin{quote}\ttfamily
+%  plainnat.bst \qquad abbrvnat.bst \qquad unsrtnat.bst
+% \end{quote}
+% These produce reference lists in the same style as the corresponding
+% standard \texttt{.bst} file, but can only be used with \thestyle{}. The
+% advantage is that they can be used in both numerical and author--year
+% mode.
+% 
+% In fact, \texttt{unsrtnat.bst} is rather silly for author--year
+% citations: the references are listed in the order they were cited, which
+% makes it difficult to find them. It is only included in case an author
+% wishes to switch from \texttt{plainnat} (author--year) to the unsorted
+% numerical mode, retaining the |\citeauthor| and |\citeyear| commands in
+% his paper.
+% 
+% It is not possible to produce a modified version of \texttt{alpha.bst}
+% since it would conflict with the |\bibitem| format of \thestyle.
+% 
+% The sample bibliography style file \texttt{natbib.bst} will no longer be
+% distributed. It merely represented a demonstration of the |\bibitem|
+% syntax for \thestyle, a function that is now taken over by
+% \texttt{plainnat.bst} and friends.
+% 
+% \section{Local Configuration}
+% For \LaTeXe, it is possible to add a local configuration file
+% \thestyle\texttt{.cfg}, which is read in, if it exists, at
+% the end of the package. It may thus contain coding to supecede that in
+% the package, although its main purpose is to allow the user to add his
+% own |\bibstyle@|\textit{bst} definitions to couple citation punctuation
+% with local bibliography styles.
+% 
+% \section{Options with \LaTeXe}\label{sec:opts}
+% One of the new features of \LaTeXe{} is \emph{options} for the packages,
+% in the same way as main styles (now called \emph{classes}) can take
+% options. This package is now installed with
+% \begin{quote}
+% |\documentclass[..]{...}|\\
+% |\usepackage[|\emph{options}|]{|\thestyle|}|
+% \end{quote}
+% The options available provide another means of specifying the
+% punctuation for citations:
+% \begin{description}
+% \item[\ttfamily round] (default) for round parentheses;
+% \item[\ttfamily square] for square brackets;
+% \item[\ttfamily curly] for curly braces;
+% \item[\ttfamily angle] for angle brackets;
+% \item[\ttfamily colon] (default) to separate multiple citations with
+%      colons;
+% \item[\ttfamily comma] to use commas as separaters;
+% \item[\ttfamily authoryear] (default) for author--year citations;
+% \item[\ttfamily numbers] for numerical citations;
+% \item[\ttfamily super] for superscripted numerical citations, as in
+%      \textsl{Nature};
+% \item[\ttfamily sort] puts multiple numerical citations in order and
+%      compresses them if possible (as 3--6, 15);
+% \item[\ttfamily sectionbib] redefines |\thebibliography| to issue
+%      |\section*| instead of |\chapter*|; valid only for classes with a
+%      |\chapter| command; to be used with the \texttt{chapterbib} package.
+% \end{description}
+% 
+% If any of these options are selected, the predefined citation styles in
+% the commands |\bibstyle@|\textit{bst} will be no longer be effective.
+% If either |\bibpunct| or |\citestyle| is given in the preamble, the above
+% punctuation options will no longer hold.
+% 
+% \section{As Module to Journal-Specific Styles}
+% Although \thestyle{} is meant to be an all-purpose bibliographic style
+% \emph{package}, it may also be incorporated as a module to other 
+% packages for specific journals. In this case, many of the general features may
+% be left off. This is allowed for with \texttt{docstrip} options that not
+% only leave off certain codelines, but also include extra ones. So far,
+% options exist for 
+% \begin{description}
+% \item[\ttfamily subpack] produces a basic version with author--year only,
+% fixed citation punctuation, no |\bibpunct| nor |\citestyle| nor 
+% predefined styles;
+% \item[\ttfamily subpack,egs] for journals of the \textsl{European Geophysical
+% Society}, in particular \textsl{Nonlinear Processes in Geophysics};
+% \item[\ttfamily subpack,agu] for \textsl{American Geophysical Union} journals.
+% \end{description}
+% The \texttt{subpack} option must always be used with \texttt{package}.
+% 
+% Previous options \texttt{jgr} and \texttt{grl} have become obsolete due
+% to revisions in these journals; they have been replaced by the more
+% general \texttt{agu} option.
+% 
+% \section{Summary}
+% 
+% The following summary is included as comments at the beginning of the
+% \thestyle\texttt{.sty} file, for quick reference. Certain lines are
+% dependent on the \texttt{docstrip} options.
+% 
+% \iffalse
+%<*package&!subpack>
+% \fi
+% \begin{verbatim}
+ % This package reimplements the LaTeX \cite command to be used for various
+ % citation styles, both author-year and numerical. It accepts BibTeX
+ % output intended for many other packages, and therefore acts as a 
+ % general, all-purpose citation-style interface.
+ %
+ % With standard numerical .bst files, only numerical citations are
+ % possible. With an author-year .bst file, both numerical and
+ % author-year citations are possible.
+ %
+ % If author-year citations are selected, \bibitem must have one of the
+ %   following forms:
+ %   \bibitem[Jones et al.(1990)]{key}...
+ %   \bibitem[Jones et al.(1990)Jones, Baker, and Williams]{key}...
+%<*apalike|all>
+ %   \bibitem[Jones et al., 1990]{key}...
+%</apalike|all>
+%<*newapa|chicago|all>
+ %   \bibitem[\protect\citeauthoryear{Jones, Baker, and Williams}{Jones
+ %       et al.}{1990}]{key}...
+ %   \bibitem[\protect\citeauthoryear{Jones et al.}{1990}]{key}...
+%</newapa|chicago|all>
+%<*astron|all>
+ %   \bibitem[\protect\astroncite{Jones et al.}{1990}]{key}...
+%</astron|all>
+%<*authordate|all>
+ %   \bibitem[\protect\citename{Jones et al., }1990]{key}...
+%</authordate|all>
+%<*harvard|all>
+ %   \harvarditem[Jones et al.]{Jones, Baker, and Williams}{1990}{key}...
+%</harvard|all>
+ %   
+ % This is either to be made up manually, or to be generated by an 
+ % appropriate .bst file with BibTeX.
+ %                            Author-year mode     ||   Numerical mode
+ % Then, \citet{key}  ==>>  Jones et al. (1990)    ||   Jones et al. [21]
+ %       \citep{key}  ==>> (Jones et al., 1990)    ||   [21]
+ % Multiple citations as normal:
+ % \citep{key1,key2}  ==>> (Jones et al., 1990; Smith, 1989) || [21,24]
+ %                           or  (Jones et al., 1990, 1991)  || [21,24]
+ %                           or  (Jones et al., 1990a,b)     || [21,24]
+ % \cite{key} is the equivalent of \citet{key} in author-year mode
+ %                         and  of \citep{key} in numerical mode
+ % Full author lists may be forced with \citet* or \citep*, e.g.
+ %       \citep*{key}      ==>> (Jones, Baker, and Williams, 1990)
+ % Optional notes as:
+ %   \citep[chap. 2]{key}    ==>> (Jones et al., 1990, chap. 2)
+ %   \citep[e.g.,][]{key}    ==>> (e.g., Jones et al., 1990)
+ %   \citep[see][pg. 34]{key}==>> (see Jones et al., 1990, pg. 34)
+ %  (Note: in standard LaTeX, only one note is allowed, after the ref.
+ %   Here, one note is like the standard, two make pre- and post-notes.)
+ %   \citealt{key}          ==>> Jones et al. 1990
+ %   \citealt*{key}         ==>> Jones, Baker, and Williams 1990
+ %   \citealt{key1,key2}    ==>> Jones et al. 1990; Smith 1989
+ % Additional citation possibilities (both author-year and numerical modes)
+ %   \citeauthor{key}     ==>> Jones et al.
+ %   \citeyear{key}       ==>> 1990
+ %   \citefullauthor{key} ==>> Jones, Baker, and Williams
+ % (Multiple keys NOT allowed!)
+ % Note: full author lists depends on whether the bib style supports them;
+ %       if not, the abbreviated list is printed even when full requested.
+ %
+ % Defining the citation style of a given bib style:
+%<!nopreonly> % Use \bibpunct (in the preamble only) with 6 mandatory arguments:
+%<nopreonly> % Use \bibpunct (anywhere in the text) with 6 mandatory arguments:
+ %    1. opening bracket for citation
+ %    2. closing bracket
+ %    3. citation separator (for multiple citations in one \cite)
+ %    4. the letter n for numerical styles, s for superscripts
+ %        else anything for author-year
+ %    5. punctuation between authors and date
+ %    6. punctuation between years when common authors missing
+ % One optional argument is the character coming before post-notes. It
+ %   appears in square braces before all other arguments. May be left off.
+ % Example (and default) \bibpunct[,]{(}{)}{;}{a}{,}{,}
+ % 
+ % To make this automatic for a given bib style, named newbib, say, make
+ % a local configuration file, natbib.cfg, with the definition
+ %   \newcommand{\bibstyle@newbib}{\bibpunct...}
+ % Then the \bibliographystyle{newbib} will cause \bibstyle@newbib to 
+ % be called on THE NEXT LATEX RUN (via the aux file).
+ %
+%<!nopreonly> % Such preprogrammed definitions may be invoked in the text (preamble only)
+%<nopreonly> % Such preprogrammed definitions may be invoked anywhere in the text
+ %  by calling \citestyle{newbib}. This is only useful if the style specified
+ %  differs from that in \bibliographystyle.
+ %
+%<*!209>
+ % With \citeindextrue and \citeindexfalse, one can control whether the
+ % \cite commands make an automatic entry of the citation in the .idx
+ % indexing file. For this, \makeindex must also be given in the preamble.
+ %
+ % LaTeX2e Options: (for selecting punctuation)
+ %   round  -  round parentheses are used (default)
+ %   square -  square brackets are used   [option]
+ %   curly  -  curly braces are used      {option}
+ %   angle  -  angle brackets are used    <option>
+ %   colon  -  multiple citations separated by colon (default)
+ %   comma  -  separated by comma
+ %   authoryear - selects author-year citations (default)
+ %   numbers-  selects numerical citations
+ %   super  -  numerical citations as superscripts
+ %   sort   -  sorts and compresses numerical citations 
+ %   sectionbib - puts bibliography in a \section* instead of \chapter*
+ % Punctuation so selected dominates over any predefined ones.
+ % LaTeX2e options are called as, e.g.
+ %        \usepackage[square,comma]{natbib}
+%</!209>
+% \end{verbatim}
+% \iffalse
+ % LaTeX the source file natbib.dtx to obtain more details.
+ %-----------------------------------------------------------
+%</package&!subpack>
+% \fi
+% 
+% \section{Options with \texttt{docstrip}}
+% The source \texttt{.dtx} file is meant to be processed with
+% \texttt{docstrip}, for which a number of options are available:
+% \begin{description}
+% \item[\ttfamily all] includes all of the other interfaces;
+%
+% \item[\ttfamily apalike] allows interpretation of minimal \texttt{apalike} 
+%    form of |\bibitem|;
+%
+% \item[\ttfamily newapa] allows |\citeauthoryear| to be in the optional 
+%    argument of |\bibitem| along with the punctuation commands of 
+%    \texttt{newapa.sty};
+%
+% \item[\ttfamily chicago] is the same as \texttt{newapa};
+%
+% \item[\ttfamily harvard] includes interpretation of |\harvarditem|;
+%
+% \item[\ttfamily astron] allows |\astroncite| to appear in the optional 
+%    argument of |\bibitem|;
+%
+% \item[\ttfamily authordate] adds the syntax of the |\citename| command.
+%
+% \end{description}
+%
+% This package file is intended to act as a module for other class files
+% written for specific journals, in which case the flexible
+% |\bibstyle@|{\em bst\/} commands are not wanted. Punctuation and
+% other style features are to be rigidly fixed. These journal options are
+% \begin{description}
+% \item[\ttfamily agu] for journals of the \textsl{American Geophysical
+%   Union};
+%
+% \item[\ttfamily egs] for journals of the \textsl{European Geophysical 
+%   Society}, in particular \textsl{Nonlinear Processes in Geophysics}.
+%
+% \end{description}
+%
+% The remaining options are:
+% \begin{description}
+% \item[\ttfamily package] to produce a \texttt{.sty} package file with most
+%     comments removed;
+% 
+% \item[\ttfamily 209] (together with \texttt{package}) for a style option 
+%     file that will run under the older \LaTeX~2.09;
+% 
+% \item[\ttfamily subpack] (together with \texttt{package}) for coding that 
+%     is to be included inside a larger package; even more comments are 
+%     removed, as well as \LaTeXe{} option handling and identification;
+%     produces a basic \thestyle\ package for author--year only, fixed
+%     citation style (punctuation);
+%
+% \item[\ttfamily nopreonly] allows |\citestyle| and |\bibpunct| to be
+%     called anywhere in the text; this is considered possibly useful
+%     with the \texttt{chapterbib} package where different chapters might 
+%     have different bibliography and citation styles; is only provided 
+%     in case I change my mind about this feature, but for now I 
+%     refuse to implement it;
+%
+% \item[\ttfamily driver] to produce a driver \texttt{.drv} file that will
+%     print out the documentation under \LaTeXe. The documentation cannot
+%     be printed under \LaTeX~2.09.
+% 
+% \end{description}
+% The source file \texttt{\filename.dtx} is itself a driver file and can
+% be processed directly by \LaTeXe.
+%
+% \StopEventually{\PrintIndex\PrintChanges}
+% 
+% \section{The Coding}
+% This section presents and explains the actual coding of the macros.
+% It is nested between |%<*package>| and |%</package>|, which
+% are indicators to \texttt{docstrip} that this coding belongs to the package 
+% file.
+%
+% The \texttt{docstrip} option |<subpack>| should only be called if the
+% coding is to be included as part of another package, in which case the 
+% announcement text and \LaTeXe{} options are suppressed.
+%
+% An alternative version of this coding is provided for running as a 
+% style file under \LaTeX~2.09. Code lines belonging to this are
+% indicated with guard |<209>|; those for LaTeXe{} only with |<!209>|.
+%
+% With \LaTeX\ release from \texttt{1995/12/01}, |\cite| is made robust, 
+% something that I have adopted as well.
+% 
+% Another change in the above release is that 
+% |\G@refundefinedtrue|\footnote{In fact, it was only proposed to be 
+%    removed, but because several packages, including this one, were 
+%    adversely affected, the name was retained for the new coding.}
+% and the |\if@openbib| flag have been removed.
+% New, more effective, and compact, coding has replaced them. Rather than
+% relying on the kernel coding, I make \thestyle\ more
+% self-reliant. 
+% 
+% \subsection{Test for Specific Journals}
+% This package should not be loaded with the specific journal packages that
+% already include it; it is superfluous and can lead to contradictions.
+%    \begin{macrocode}
+%<*package>
+%<*!209&!subpack>
+\@ifclassloaded{aguplus}{\PackageError{natbib}
+  {The aguplus class already includes natbib coding,\MessageBreak
+   so you should not add it explicitly}
+  {Type <Return> for now, but then later remove\MessageBreak
+   the command \protect\usepackage{natbib} from the document}
+  \endinput}{}
+\@ifclassloaded{nlinproc}{\PackageError{natbib}
+  {The nlinproc class already includes natbib coding,\MessageBreak
+   so you should not add it explicitly}
+  {Type <Return> for now, but then later remove\MessageBreak
+   the command \protect\usepackage{natbib} from the document}
+  \endinput}{}
+\@ifclassloaded{egs}{\PackageError{natbib}
+  {The egs class already includes natbib coding,\MessageBreak
+   so you should not add it explicitly}
+  {Type <Return> for now, but then later remove\MessageBreak
+   the command \protect\usepackage{natbib} from the document}
+  \endinput}{}
+%</!209&!subpack>
+%    \end{macrocode}
+%
+% \subsection{Selecting Citation Punctuation and Other Modifications}
+% \begin{macro}{\bibstyle@xxx}
+% \changes{5.3}{1994 Sep 13}{Add \texttt{agsm} and \texttt{dcu} punctuation 
+%    styles from \texttt{harvard} series}
+% We begin by defining a number of punctuation styles for specific
+% author--year \texttt{.bst} files that I use. 
+% They are placed here, near the beginning, so that another
+% user can easily find them to add his own. Some comments remain in the
+% stripped version too.
+%    \begin{macrocode}
+%<*!subpack>
+ % Define citation punctuation for some author-year styles
+ % One may add and delete at this point
+%<!209> % Or put additions into local configuration file natbib.cfg
+\newcommand\bibstyle@chicago{\bibpunct{(}{)}{;}{a}{,}{,}}
+\newcommand\bibstyle@named{\bibpunct{[}{]}{;}{a}{,}{,}}
+\newcommand\bibstyle@agu{\bibpunct{[}{]}{;}{a}{,}{,~}}%Amer. Geophys. Union
+\newcommand\bibstyle@egs{\bibpunct{(}{)}{;}{a}{,}{,}}%Eur. Geophys. Soc.
+%<*all|harvard>
+\newcommand\bibstyle@agsm{\bibpunct{(}{)}{,}{a}{}{,}\gdef\harvardand{\&}}
+\newcommand\bibstyle@kluwer{\bibpunct{(}{)}{,}{a}{}{,}\gdef\harvardand{\&}}
+\newcommand\bibstyle@dcu{\bibpunct{(}{)}{;}{a}{;}{,}\gdef\harvardand{and}}
+%</all|harvard>
+%    \end{macrocode}
+% 
+% Here give the explicit punctuation for the specific journals; their
+% coding need not contain the punctuation macros |\bibpunct| and
+% |\bibstyle@xxx| since the punctuation is fixed for them.
+%    \begin{macrocode}
+\newcommand\bibstyle@aa{\bibpunct{(}{)}{;}{a}{}{,}} %Astronomy & Astrophysics
+\newcommand\bibstyle@pass{\bibpunct{(}{)}{;}{a}{,}{,}}%Planet. & Space Sci
+\newcommand\bibstyle@anngeo{\bibpunct{(}{)}{;}{a}{,}{,}}%Annales Geophysicae
+\newcommand\bibstyle@nlinproc{\bibpunct{(}{)}{;}{a}{,}{,}}%Nonlin.Proc.Geophys.
+%</!subpack>
+%<agu>\newcommand\NAT@open{[} \newcommand\NAT@close{]} 
+%<agu>\newcommand\NAT@sep{;} \newcommand\NAT@cmt{,}
+%<agu>\newcommand\NAT@aysep{,} \newcommand\NAT@yrsep{,~}
+%<egs>\newcommand\NAT@open{(} \newcommand\NAT@close{)} 
+%<egs>\newcommand\NAT@sep{;} \newcommand\NAT@cmt{,}
+%<egs>\newcommand\NAT@aysep{,} \newcommand\NAT@yrsep{,}
+%    \end{macrocode}
+% 
+% \changes{6.5}{1997 Jan 30}{Fix \texttt{esa} style for new note system}
+% Next, the same thing is done for some numerical styles. A major
+% difference here is that the |\@biblabel| and |\@cite| commands must also
+% be redefined in many cases. These redefinitions must be made with the
+% |\gdef| (global definition) command.
+%    \begin{macrocode}
+%<*!subpack>
+ % Define citation punctuation for some numerical styles
+\newcommand\bibstyle@cospar{\bibpunct{/}{/}{,}{n}{}{}%
+     \gdef\NAT@biblabelnum##1{##1.}}
+\newcommand\bibstyle@esa{\bibpunct{(}{)}{,}{n}{}{}%
+     \gdef\NAT@biblabelnum##1{##1.\hspace{1em}}%
+     \gdef\NAT@citenum##1##2##3{\NAT@open \if\relax##2\relax\else
+       ##2\ \fi Ref.~##1\if\relax##3\relax\else\NAT@cmt\ ##3\fi\NAT@close}}
+\newcommand\bibstyle@nature{\bibpunct{}{}{,}{s}{}{}%
+     \gdef\NAT@biblabelnum##1{##1.}}
+%    \end{macrocode}
+% 
+% Finally, the standard \LaTeX{} (numerical) citation styles are included
+%  along with their \thestyle\ modifications (author--year).
+%    \begin{macrocode}
+ % The standard LaTeX styles
+\newcommand\bibstyle@plain{\bibpunct{[}{]}{,}{n}{}{}}
+\let\bibstyle@alpha=\bibstyle@plain
+\let\bibstyle@abbrv=\bibstyle@plain
+\let\bibstyle@unsrt=\bibstyle@plain
+ % The author-year modifications of the standard styles
+\newcommand\bibstyle@plainnat{\bibpunct{[}{]}{,}{a}{,}{,}}
+\let\bibstyle@abbrvnat=\bibstyle@plainnat
+\let\bibstyle@unsrtnat=\bibstyle@plainnat
+%    \end{macrocode}
+% \end{macro}
+% 
+% \subsection{\LaTeXe{} Options}
+% \begin{macro}{\ifNAT@numbers}
+% \changes{5.5}{1995 Mar 21}{Add flag for switching between cite styles}
+% \begin{macro}{\ifNAT@super}
+% \changes{5.5}{1995 Mar 21}{Add flag for switching between cite styles}
+% Two flags are used to keep track of the citation style. The flag
+% |\ifNAT@numbers| is \meta{false} by default (author--year) and switches
+% to \meta{true} for numerical citations. The flag |\ifNAT@super| indicates
+% if the numerical citation is to be done with superscripts.
+%    \begin{macrocode}
+\newif\ifNAT@numbers \NAT@numbersfalse
+\newif\ifNAT@super \NAT@superfalse
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\DeclareOption}
+% \changes{5.0}{1994 May 18}{Add \LaTeXe{} options.}
+% \changes{5.3}{1994 Sep 13}{Add options \texttt{angle} and \texttt{curly}}
+% \changes{6.0}{1995 Sep 6}{Add option \texttt{bibstyle}}
+% \changes{6.0}{1995 Sep 6}{Execute \texttt{nobibstyle} with all options}
+% \changes{6.1}{1995 Nov 27}{Add option \texttt{openbib}}
+% \changes{6.4}{1996 Sep 1}{Add option \texttt{sectionbib}}
+% \changes{6.4}{1996 Sep 13}{Add option \texttt{sort}}
+% For \LaTeXe, we can define some options to be used with the |\usepackage|
+% command that loads the \thestyle{} package. These are an additional means
+% of specifying the citation punctuation and scheme.
+% 
+% The standard option \texttt{openbib} is also defined here so that its
+% behaviour is entirely under my control. Relying on the standard classes
+% can lead to trouble.
+%    \begin{macrocode}
+%<*!subpack&!209>
+\DeclareOption{numbers}{\NAT@numberstrue
+   \ExecuteOptions{square,comma,nobibstyle}}
+\DeclareOption{super}{\NAT@supertrue\NAT@numberstrue
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{authoryear}{\NAT@numbersfalse
+   \ExecuteOptions{round,colon,bibstyle}}
+\DeclareOption{round}{%
+      \renewcommand\NAT@open{(} \renewcommand\NAT@close{)}
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{square}{%
+      \renewcommand\NAT@open{[} \renewcommand\NAT@close{]}
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{angle}{%
+      \renewcommand\NAT@open{$<$} \renewcommand\NAT@close{$>$}
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{curly}{%
+      \renewcommand\NAT@open{\{} \renewcommand\NAT@close{\}}
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{comma}{\renewcommand\NAT@sep{,}
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{colon}{\renewcommand\NAT@sep{;}
+   \ExecuteOptions{nobibstyle}}
+\DeclareOption{nobibstyle}{\let\bibstyle=\@gobble}
+\DeclareOption{bibstyle}{\let\bibstyle=\@citestyle}
+\newif\ifNAT@openbib \NAT@openbibfalse
+\DeclareOption{openbib}{\NAT@openbibtrue}
+\DeclareOption{sectionbib}{\def\NAT@sectionbib{on}}
+\def\NAT@sort{0}
+\DeclareOption{sort}{\def\NAT@sort{1}}
+\@ifpackageloaded{cite}{\PackageWarningNoLine{natbib}
+  {The `cite' package should not be used\MessageBreak
+   with natbib. Use option `sort' instead}\ExecuteOptions{sort}}{}
+%</!subpack&!209>
+%    \end{macrocode}
+% Before version~6.0, the punctuation options had the lowest priority,
+% being overridden by any |\bibstyle@|\textit{bst} command. It was necessary
+% to add the option \texttt{nobibstyle} to make them effective. Now this
+% option is automatically executed whenever a punctuation option is chosen.
+% The reason is that \texttt{nobibstyle} is either superfluous (no
+% predefined citation style is present) or always necessary to make the
+% other options meaningful. 
+% 
+% It seems to be better practice to make any explicit choices to have
+% higher priority over implicit ones.
+% 
+% The option \texttt{bibstyle} reactivates the predefined commands, just in
+% case this is needed, as it is for the option \texttt{authoryear}. This
+% leaves the predefined styles functioning, since it does not really
+% determine the citation style, but rather establishes a default which may
+% be overwritten by a prestored one.  For this reason, this option must be
+% defined very early so that any explicit punctuation options overwrite the
+% defaults. (Options are executed in the order defined.)
+% 
+% \end{macro}
+%
+% \subsection{Selecting Citation Punctuation and Other Modifications}
+% \begin{macro}{\bibstyle}
+% \changes{5.4}{1994 Nov 24}{Move \cs{ProcessOptions} to after definition
+%    of \cs{bibstyle}}
+% The pre-defined punctuation styles are associated with particular
+% \texttt{.bst} files. This is implemented by means of the standard
+% |\bibliographystyle| command that specifies the name of the \texttt{.bst}
+% file that is to be used by \btx. Some \LaTeX{} manuals erroneously state
+% that this command must be issued prior to any |\cite| commands. If that
+% were the case, the task of invoking the style definitions would be much
+% easier, for they certainly must be issued before the first |\cite|.
+% However, I have always called |\bibliographystyle| together with
+% |\bibliography|, well after all |\cite| commands. 
+% 
+% In fact, all that |\bibliographystyle|\marg{bst} does is to write
+% |\bibstyle|\marg{bst} to the auxiliary file. This file, and all its
+% contents, will be read in at the beginning of the next \LaTeX{} run; to
+% be precise, it is read in by |\begin{document}|. The command |\bibstyle| is
+% then executed at that point on the next run. However, it is 
+% defined to do nothing more than to swallow up its argument! In other
+% words, the combination |\bibliographystyle| and |\bibstyle| do absolutely
+% nothing to the \LaTeX{} runs. In fact, |\bibstyle| is a command for
+% \btx{} alone.
+% 
+% I have taken advantage of this to redefine |\bibstyle| to execute the
+% \texttt{bst}-specific definitions. This definition is made here before
+% |\ExecuteOptions| so that options may make use of it; the option
+% \texttt{nobibstyle} turns it off, for example.
+%    \begin{macrocode}
+%<*!subpack>
+\renewcommand\bibstyle[1]{\@ifundefined{bibstyle@#1}{\relax}
+     {\csname bibstyle@#1\endcsname}}
+%    \end{macrocode}
+% This is executed only when the auxiliary file is read in, and that is
+% when |\begin{document}| is issued. Thus this is well before any |\cite|
+% commands. It is for this reason that any definitions in the
+% |\bibstyle@xxx| commands must be global.
+% 
+% A minor problem arises in that the auxiliary file is read in a second
+% time, at the end of the run, to check whether any labels have changed. 
+% Sometimes, re-executing the |\bibstyle@xxx| command at this point
+% produces error messages. To avoid this, |\bibstyle| is reset to its
+% normal, do-nothing, definition after |\begin{document}|.
+% 
+% \LaTeXe{} provides a better way of adding commands to |\document|,
+% which is then exploited here. Paradoxically, the problem with re-reading
+% the auxiliary file does not seem to arise for this version.
+% 
+% (|\NAT@set@cites| must also be executed at the start of the document; for
+% \LaTeXe, this is added later when the macro is defined.)
+%    \begin{macrocode}
+%<*209>
+\let\ori@document=\document
+\renewcommand\document{\ori@document\global\let\bibstyle=\@gobble 
+  \NAT@set@cites}
+%</209>
+%<!209>\AtBeginDocument{\global\let\bibstyle=\@gobble}
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\citestyle}
+% \changes{5.4}{1995 Feb 03}{Add macro}
+% \changes{5.5}{1995 Mar 24}{Make preamble only}
+% To allow one to invoke preprogrammed punctuation styles that are
+% different from the name of the bibliography style specified by
+% |\bibliographystyle|, call |\citestyle| in the preamble. This then
+% deactivates |\bibstyle| so that any preprogrammed punctuations become
+% ineffective.
+% 
+% This, and all other punctuation (citation style) declarations, may only
+% be used in the preamble, as of version 5.5. (Previously they could only
+% be used after the preamble, but the preamble is more logical.)
+%    \begin{macrocode}
+\let\@citestyle\bibstyle
+\newcommand\citestyle[1]{\@citestyle{#1}\let\bibstyle\@gobble}
+%<!209&!nopreonly>\@onlypreamble{\citestyle}\@onlypreamble{\@citestyle}
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\bibpunct}
+% \changes{5.4}{1994 Nov 24}{Add superscript style of citations}
+% \changes{5.5}{1995 Mar 21}{Use flags to select citation style}
+% \changes{5.5}{1995 Mar 24}{Make preamble only}
+% \changes{6.0}{1995 Sep 6}{Sets \cs{bibstyle} to \cs{@gobble}}
+% \changes{6.0}{1995 Sep 6}{Declare \cs{NAT@numbersfalse} before testing 4th
+%      argument}
+% \changes{6.0}{1995 Sep 19}{Add optional argument for \cs{NAT@cmt}}
+% Now |\bibpunct| is defined. It sets various punctuation commands equal to
+% its arguments. It also switches to numerical style if that is specified
+% by the fourth argument. This is done by setting the citation style
+% flag |NAT@numbers| accordingly. The internal cite macros are later
+% set to the style-dependent definitions by calling |\NAT@set@cites|.
+% 
+% The fourth argument can also be \texttt{s} for superscript, which
+% sets both the numerical and the |\NAT@super| flags.
+% 
+% An optional argument has been added to determine the punctuation that
+% precedes a trailing note. This makes the counting of mandatory arguments
+% somewhat confused, since the fourth argument is now |#5|.
+% 
+%    \begin{macrocode}
+%<!209>\newcommand\bibpunct[7][,]%
+%<209>\newcommand\bibpunct{\@ifnextchar[{\@bibpunct}{\@bibpunct[,]}}
+%<209>\def\@bibpunct[#1]#2#3#4#5#6#7%
+  {\gdef\NAT@open{#2}\gdef\NAT@close{#3}\gdef
+   \NAT@sep{#4}\global\NAT@numbersfalse\ifx #5n\global\NAT@numberstrue
+   \else
+   \ifx #5s\global\NAT@numberstrue\global\NAT@supertrue
+   \fi\fi
+   \gdef\NAT@aysep{#6}\gdef\NAT@yrsep{#7}%
+   \gdef\NAT@cmt{#1}%
+   \global\let\bibstyle\@gobble
+%<nopreonly>   \NAT@set@cites
+  }
+%<*!nopreonly>
+%<!209>\@onlypreamble{\bibpunct}
+%<209>\def\do{\noexpand\do\noexpand}
+%<209>\edef\@preamblecmds{\@preamblecmds \do\bibpunct \do\citestyle}
+%</!nopreonly>
+%</!subpack>
+%    \end{macrocode}
+% The command turns off |\bibstyle| so that the predefined
+% |\bibstyle@|\textit{bst} commands no longer work. Thus |\bibpunct| has
+% priority over the predefined styles.
+% \end{macro}
+% 
+% \subsection{Setting the Defaults}
+% For \LaTeXe, the defaults (punctuation and scheme type) are set with the
+% |\ExecuteOptions| command. For \LaTeX~2.09, the default scheme is
+% author--year, and punctuation can only be set with |\bibpunct|.
+%
+% \begin{macro}{\NAT@open}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@citebegin}}
+% \begin{macro}{\NAT@close}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@citeend}}
+% \begin{macro}{\NAT@sep}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@citesep}}
+% \begin{macro}{\NAT@aysep}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@auyrsep}}
+% \begin{macro}{\NAT@yrsep}
+% \changes{5.5}{1995 May 14}{Renamed from \cs{@yrsep}}
+% \begin{macro}{\NAT@cmt}
+% \changes{6.0}{1995 Sep 19}{Add macro}
+% The five punctuation characters for citations are the start and stop
+% brackets, the character between multiple citations, the character between
+% the authors and year (parenthetical only), and the character between
+% adjacent years when the common author list is omitted. 
+% A sixth one has been added: the character preceding post-notes.
+% Define their default values. 
+%    \begin{macrocode}
+%<!agu&!egs>\newcommand\NAT@open{(} \newcommand\NAT@close{)} 
+%<!agu&!egs>\newcommand\NAT@sep{;} 
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
+% \changes{6.0}{1995 Sep 19}{Remove \cs{ExecuteOptions} since default
+%        style determined by definitions}
+% The option \texttt{authoryear} was originally provided to serve as the
+% default; hence its definition includes \texttt{bibstyle}. However, this
+% is not necessary since all the appropriate parameters are set to these
+% values anyway. (One could consider removing \texttt{bibstyle}.)
+%    \begin{macrocode}
+%<*!subpack&!209>
+%\ExecuteOptions{authoryear}
+\ProcessOptions
+%</!subpack&!209>
+%<!agu&!egs>\newcommand\NAT@aysep{,} \newcommand\NAT@yrsep{,}
+%<!agu&!egs>\newcommand\NAT@cmt{,}
+%    \end{macrocode}
+%
+% \subsection{Internal Citing Macros}
+% A number of internal macros (|\@citex|, |\@cite|, |\@biblabel|, and
+% |\@bibsetup|) need to have different definitions for author--year and
+% numerical schemes. They are defined here for the two different styles,
+% with different names, and which ones become active depend on the citation
+% style flags |\ifNAT@numbers| and |\ifNAT@super|.
+% 
+% The coding for the journals always defines the internal macros directly
+% as the author--year version, since they can never do any switching.
+% 
+% \begin{macro}{\@cite}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+%      author--year definition}
+% \begin{macro}{\NAT@cite}
+% \changes{4.2}{1993 Dec 2}{Reversed optional text no longer needs to include
+%       a trailing blank}
+% \changes{5.0}{1994 May 18}{Add optional notes after as well as before
+%      citation.}
+% \changes{5.5}{1995 Mar 13}{Add command space in place of space}
+% \changes{5.5}{1995 Mar 13}{Use \cs{if}\cs{relax}\texttt{\#2}\cs{relax}
+%    in place of \cs{if}\texttt{\#2}\cs{@empty}}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@cite}}
+% \begin{macro}{\NAT@citenum}
+% \changes{5.0}{1994 May 18}{Add optional notes after as well as before
+%      citation.}
+% \changes{5.5}{1995 Mar 13}{Add command space in place of space}
+% \changes{5.5}{1995 Mar 13}{Use \cs{if}\cs{relax}\texttt{\#2}\cs{relax}
+%    in place of \cs{if}\texttt{\#2}\cs{@empty}}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citenum}}
+% \begin{macro}{\NAT@citesuper}
+% \changes{5.4}{1994 Nov 24}{Add macro for superscripts}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citesuper}}
+% \changes{5.5}{1995 Mar 27}{Prints post-note only if present}
+% \changes{6.2}{1995 Feb 2}{Get superscript font size right; use
+%       \cs{textsuperscript}}
+% \changes{6.5}{1997 Jan 30}{Numericals always print notes if present, do not
+%    test for any flag first}
+% Define the internal |\@cite| commands that prints the assembled string
+% of citation label texts, plus possible optional notes, before and after.
+% The numerical version is almost the same, except that the brackets
+% |\NAT@open| and |\NAT@close| are always present and the optional notes are
+% included if they are present. For author-year, the notes are included (if
+% present) here only for parenthetical citations (|\ifNAT@swa| if \meta{true})
+% and for textual citations, they are printed by the |\NAT@citex|.
+%
+% The superscript citation prints only the following, not the preceding,
+% note, and then only if it is present.
+%    \begin{macrocode}
+%<subpack>\renewcommand\@cite%
+%<!subpack>\newcommand\NAT@cite%
+    [3]{\ifNAT@swa\NAT@open\if\relax#2\relax\else#2\ \fi
+        #1\if\relax#3\relax\else\NAT@cmt\ #3\fi\NAT@close\else#1\fi}
+%<*!subpack>
+\newcommand\NAT@citenum[3]{\NAT@open\if\relax#2\relax\else
+   #2\ \fi #1\if\relax#3\relax\else\NAT@cmt\ #3\fi\NAT@close}
+\newcommand\NAT@citesuper[3]{\unskip\hspace{1pt}\textsuperscript{#1}%
+   \if\relax#3\relax\else\ (#3)\fi}
+%<!209>\providecommand
+%<209>\newcommand
+  \textsuperscript[1]{\mbox{$^{\mbox{\scriptsize#1}}$}}
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}
+% 
+% \begin{macro}{\@citex}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+%      author--year definition}
+% \changes{6.1}{1995 Nov 22}{Use \cs{NAT@citeundefined}}
+% \begin{macro}{\NAT@citexnum}
+% \changes{5.4}{1994 Nov 24}{Make like \LaTeXe{} definition instead of 2.09}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citexnum}}
+% \changes{6.0}{1995 Sep 4}{Prints \cs{NAT@num} instead of \cs{b@citeb}}
+% \changes{6.4}{1996 Sep 12}{Add \cs{NAT@space} for variable spacing between
+%        numericals and superscripts}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% The original definition of |\@citex| is now used to define |\NAT@citexnum|,
+% the version for numerical citations. What it does is to write a
+% |\citation| command to the auxiliary file (for \btx), and then parses the
+% second argument, the list of citation keys. These keys have to be decoded
+% into the actual label text contained in |\b@|\emph{key} (a number or
+% author--year), and put together as the argument of |\@cite|. 
+% 
+% The temporary command |\@citeb| takes on the value of each of the keys in
+% turn; |\@citea| is the separator between multiple citations, initially
+% set to nothing, becoming |\NAT@sep| plus line-break suppression
+% afterwards. The |\@firstofone| macro removes any leading blanks in
+% |\@citeb|, making |\cite{key1, key2}| possible. If |\b@|\emph{key} is
+% not defined (as on the first run, for example), a warning is printed, and
+% a question mark inserted. Finally, the decoded label text is placed into
+% an |\hbox| to prevent it from being split.
+%  
+% As of version 6.0, the numerical label text is to be found in |\NAT@num|,
+% whereas previously it was the entire label, |\b@|\emph{key}.
+% 
+% Note that here, and in later coding, internal names beginning with
+% |\@cite..| are employed; these names are used in the original \LaTeX{}
+% coding for the same functions. Therefore, if there are other packages
+% that have name conflicts with \thestyle, they will also have conflicts with
+% standard \LaTeX\ too.
+% 
+% For compatibility with the \texttt{chapterbib} package of Donald Arseneau,
+% add |\@extra@b@citeb| to the cite key; this contains the number of the 
+% included file in order to distinguish the same citation in separate files
+% which then belong to different bibliography listings.
+% \begin{macrocode} 
+%<209>\let\@firstofone\@iden
+%<!209>\providecommand\@firstofone[1]{#1}
+%<*!subpack>
+\newcommand\NAT@citexnum{}
+\def\NAT@citexnum[#1][#2]#3{\let\@citea\@empty
+  \@cite{\@for\@citeb:=#3\do
+    {\@citea\def\@citea{\NAT@sep\penalty\@m\NAT@space}%
+     \edef\@citeb{\expandafter\@firstofone\@citeb}%
+     \if@filesw\immediate\write\@auxout{\string\citation{\@citeb}}\fi
+     \@ifundefined{b@\@citeb\@extra@b@citeb}{%
+%<209>       {\reset@font\bf ?}\@warning
+%<!209>{\reset@font\bfseries?}
+%<!209>        \NAT@citeundefined\PackageWarning{natbib}%
+       {Citation `\@citeb' on page \thepage \space undefined}}%
+     {\NAT@parse{\@citeb}\hbox{\hyper@natlinkstart{\@citeb}%
+      \NAT@num\hyper@natlinkend}}}}{#1}{#2}}
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\NAT@citex}
+% \changes{5.2}{1994 Aug 25}{Make like \LaTeXe{} definition instead of 2.09}
+% \changes{5.4}{1994 Nov 24}{Change space to command space for text cites}
+% \changes{5.4}{1995 Feb 6}{Add test for adjacent citations having equal
+%   authors and years}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@citex}}
+% \changes{6.0}{1995 Sep 21}{Move \cs{ifNAT@full} test from
+%          \cs{NAT@parse} to here}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% The author--year version of |\@citex| is now defined.
+% It starts off much the same as the numerical version. However, it wants
+% the authors and year for each decoded label text to be separated into
+% |\NAT@nm| and |\NAT@date|. This is done by the routine |\NAT@parse|.
+% The names of the authors in the previous key are stored in
+% |\NAT@last@nm|,
+% and if that is the same as the current names, it is not printed again.
+% The output citation text is not put into an |\hbox| since line division
+% may occur within the author--year citation. The output is formatted
+% differently for parenthetical (|\NAT@swa| \meta{true}) and textual
+% (|\NAT@swa| \meta{false}) cases.
+% 
+% |\NAT@nm| will contain either |\NAT@name| or |\NAT@all@names| depending
+% on the state of |\ifNAT@full|.
+%    \begin{macrocode}
+%<subpack>\def\@citex%
+%<!subpack>\newcommand\NAT@citex{}
+%<!subpack>\def\NAT@citex%
+  [#1][#2]#3{\let\@citea\@empty
+  \@cite{\let\NAT@nm\@empty\let\NAT@year\@empty
+    \@for\@citeb:=#3\do
+    {\edef\@citeb{\expandafter\@firstofone\@citeb}%
+     \if@filesw\immediate\write\@auxout{\string\citation{\@citeb}}\fi
+     \@ifundefined{b@\@citeb\@extra@b@citeb}{\@citea%
+%<209>       {\reset@font\bf ?}\@warning
+%<!209>       {\reset@font\bfseries ?}\NAT@citeundefined
+%<!209>                 \PackageWarning{natbib}%
+       {Citation `\@citeb' on page \thepage \space undefined}}%
+     {\hyper@natlinkstart{\@citeb}%
+     \let\NAT@last@nm=\NAT@nm\let\NAT@last@yr=\NAT@year
+     \NAT@parse{\@citeb}\ifNAT@full\let\NAT@nm\NAT@all@names\else
+       \let\NAT@nm\NAT@name\fi
+%    \end{macrocode}
+% Begin parenthetical citation. Check if author names the same as in the
+% previous citation, and if so, also check if the years are the same.
+% \changes{5.4}{1995 Feb 8}{Add \cs{unskip} to avoid double spacing
+%     between years}
+% \changes{6.5}{1997 Jan 30}{Add optional notes for textual citations}
+% If so, citations are printed `1994a,b'; if a space is wanted between
+%  the letters, as `1994a,~b', then give |\NAT@yrsep| as |{,~}|. For this
+%  reason, the |\unskip| is needed when the space between years is printed
+%  to avoid two spaces.
+%    \begin{macrocode}
+     \ifNAT@swa
+       \ifx\NAT@last@nm\NAT@nm\NAT@yrsep
+          \ifx\NAT@last@yr\NAT@year \NAT@exlab\else\unskip\ \NAT@date\fi
+       \else\@citea{\NAT@nm}\NAT@aysep
+       \ \NAT@date \fi \def\@citea{\NAT@sep\ }%
+%    \end{macrocode}
+% Begin textual citation. Do same checks for repeated names and years.
+% Optional notes are added here, not in |\NAT@cite|, which means for 
+% multiple citations, each one will receive the notes in the year part.
+% (Pre-notes are questionable for this, but include them anyway.)
+%    \begin{macrocode}
+     \else
+       \ifx\NAT@last@nm\NAT@nm\NAT@yrsep\ifx\NAT@last@yr\NAT@year 
+         \NAT@exlab\else \unskip\ \NAT@date\fi
+       \else\@citea{\NAT@nm}\ \NAT@open\if\relax#1\relax\else#1\ \fi
+         \NAT@date\fi
+       \def\@citea{\NAT@close\NAT@sep\ }%
+     \fi \hyper@natlinkend
+     }}\ifNAT@swa\else\if\relax#2\relax\else\NAT@cmt\ #2\fi
+     \NAT@close\fi}{#1}{#2}}
+%    \end{macrocode}
+%
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\@biblabel}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+%      author--year definition}
+% \begin{macro}{\NAT@biblabel}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@biblabel}}
+% \begin{macro}{\NAT@biblabelnum}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@biblabelnum}}
+% Similarly for the |\@biblabel| command, that is used to format the
+% citation label in the list of references, define the author--year 
+% and the numerical versions. For the former, no labels are
+% printed in the list of references.
+%    \begin{macrocode}
+%<subpack>\renewcommand\@biblabel[1]{\hfill}
+%<*!subpack>
+\newcommand\NAT@biblabel[1]{\hfill}
+\newcommand\NAT@biblabelnum[1]{[#1]}
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+% 
+% \begin{macro}{\@bibsetup}
+% \changes{5.5}{1995 Mar 21}{Is \cs{let} equal to the numerical or
+%      author--year definition}
+% \begin{macro}{\NAT@bibsetup}
+% \changes{5.5}{1995 Mar 13}{Add \cs{bibhang} for variable hanging
+%          indentation}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@bibsetup}}
+% \begin{macro}{\NAT@bibsetnum}
+% \changes{5.1}{1994 Jun 22}{Add \cmd{\if@openbib} as in \LaTeXe}
+% \changes{5.5}{1995 Mar 21}{Renamed from \cs{@bibsetnum}}
+% \changes{6.1}{1995 Nov 22}{Use \cs{ifNAT@openbib}}
+% \changes{6.2}{1996 Mar 05}{Add \cs{bibsep} for linespacing between
+%               references}
+% \changes{6.5}{1997 Jan 10}{Set \cs{bibsep} to 0 for EGS}
+% The macro |\@bibsetup| is called by |\thebibliography| and contains any
+% coding for formatting the list of references that may be different for
+% numerical and author--year schemes.  For numerical citations, the
+% |\labelwidth| must be set to the size of the longest label (the argument
+% of |\thebibliography|), and the |\leftmargin| adjusted accordingly. For
+% author--year, there are no labels, so |\labelwidth| is zero, all lines
+% after the first are indented by 1~em.
+% 
+% Since |\thebibliography| is not included in the \textsl{AGU} package,
+% this macro is left off here too.
+%    \begin{macrocode}
+%<*!agu>
+%<*!egs>
+%<*!subpack>
+\newcommand\NAT@bibsetnum[1]{\settowidth\labelwidth{\@biblabel{#1}}%
+   \setlength{\leftmargin}{\labelwidth}\addtolength{\leftmargin}{\labelsep}%
+   \setlength{\itemsep}{\bibsep}\setlength{\parsep}{\z@}%
+%<*!209>
+   \ifNAT@openbib
+     \addtolength{\leftmargin}{\bibindent}%
+     \setlength{\itemindent}{-\bibindent}%
+     \setlength{\listparindent}{\itemindent}%
+     \setlength{\parsep}{0pt}%
+   \fi
+%</!209>
+}
+%</!subpack>
+%</!egs>
+\newlength{\bibhang}
+\setlength{\bibhang}{1em}
+%    \end{macrocode}
+%
+% The length |\bibsep| is to be the spacing between listed references.
+% This is normally the regular line spacing between |\item|s in a
+% \texttt{list} environment, which is |\itemsep| + |\parsep|. These are set
+% by |\@listi|. Therefore, in order to set |\bibsep| to the default value,
+% call |\@listi| locally and globally set it.
+%
+%    \begin{macrocode}
+\newlength{\bibsep}
+%<!egs>{\@listi \global\bibsep\itemsep \global\advance\bibsep by\parsep}
+%<egs>\setlength{\bibsep}{\z@}
+
+%<subpack>\newcommand\@bibsetup%
+%<!subpack>\newcommand\NAT@bibsetup%
+   [1]{\setlength{\leftmargin}{\bibhang}\setlength{\itemindent}{-\leftmargin}%
+       \setlength{\itemsep}{\bibsep}\setlength{\parsep}{\z@}}
+%</!agu>
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+% 
+% \begin{macro}{\NAT@set@cites}
+% \changes{5.5}{1995 Mar 21}{New macro to set the internal macros to
+%         numerical or author--year}
+% \changes{6.3}{1996 Jun 17}{Add \cs{natexlab}}
+% \changes{6.4}{1996 Sep 12}{Remove \cs{global} from definitions and \cs{let}}
+% \changes{6.4}{1996 Sep 12}{Define \cs{NAT@space} differently for 
+%        numericals and superscripts}
+% The four internal macros that have different definitions depending on the
+% citation style have been defined with different names; now set the macros
+% to be executed to that set that is actually wanted. This is determined by
+% the flags |\ifNAT@numbers| and |\ifNAT@super|. The setting command 
+% |\NAT@set@cites| is executed by |\begin{document}|, after which point,
+% the citation style should be frozen.
+%
+% The command |\natexlab| is used in the \texttt{.bst} files to enclose the
+% extra labels (the letters added to the dates); these are to be suppressed
+% for numerical citations.
+%    \begin{macrocode}
+%<*!subpack>
+\newcommand\NAT@set@cites{\ifNAT@numbers
+  \ifNAT@super \let\@cite\NAT@citesuper 
+     \let\NAT@space\relax\else
+     \let\@cite\NAT@citenum \def\NAT@space{ }\fi
+  \let\@citex\NAT@citexnum
+  \let\@biblabel\NAT@biblabelnum
+  \let\@bibsetup\NAT@bibsetnum
+  \def\natexlab##1{}%
+ \else
+  \let\@cite\NAT@cite
+  \let\@citex\NAT@citex
+  \let\@biblabel\NAT@biblabel
+  \let\@bibsetup\NAT@bibsetup
+  \def\natexlab##1{##1}%
+ \fi}
+%<!209>\AtBeginDocument{\NAT@set@cites}
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}
+%
+% \changes{6.5}{1997 Jan 30}{Add \texttt{showkeys} coding for \cs{@citex}}
+% Since |\citep|, |\citet|, and |\citealt| are all ultimately defined in 
+% terms of the |\@citex| command, the best way to get the \texttt{showkeys}
+% package to handle these is to let it accommodate only |\@citex|. David
+% Carlisle has allowed for \thestyle, but only for |\cite| with variable number
+% of arguments, |\citeauthor|, |\citefullauthor|, and |\citeyear|. Add the
+% necessary coding at the beginning, after we know if \texttt{showkeys}
+% has been loaded or not, and |\@citex| has its final definition.
+%    \begin{macrocode}
+%<*!209>
+\AtBeginDocument{\@ifpackageloaded{showkeys}{%
+\let\SK@citex\@citex
+       \def\@citex[#1][#2]#3{\SK@\SK@@ref{#3}\SK@citex[#1][#2]{#3}}
+}{}}
+%</!209>
+%    \end{macrocode}
+%
+% \subsection{The Citations}
+%
+% \begin{macro}{\citet}
+% \changes{6.2}{1996 Jan 11}{Add macro for textual cite in numerical mode}
+% \changes{6.5}{1997 Jan 30}{Make this standard textual citation, with notes}
+% Textual citations are made with the |\citet| command, which has a starred
+% form for full authors, and may have one or two optional arguments for notes.
+%
+% This command is equivalent to the older syntex |\cite|\marg{key} without
+% optional arguments, at least in author--year mode. In numerical mode,
+% it prints the authors and then the numerical reference, whereas |\cite|
+% will only print the number. This simplifies the switching between the two
+% modes with minimal changes in text. One wants to replace ``as shown by Jones
+% et~al.\ (1990)'' with ``as shown by Jones et~al.\ [21]''; with |\cite|,
+% one would get ``as shown by [21]''. 
+%
+% This is such a practical idea, that I have decided to make it the standard
+% means of textual citing. It now even allows optional notes in textual cites,
+% something that I have been asked to provide, and which is impossible under 
+% the old syntex with |\cite|.
+%
+% Note that the flag |\ifNAT@swa| determines if the citation is textual or
+% parenthetical, and |\ifNAT@full| whether abbreviated or full author names
+% are to be printed.
+%    \begin{macrocode}
+\newif\ifNAT@full\NAT@fullfalse
+\newif\ifNAT@swa
+%<209>\renewcommand\citet
+%<!209>\DeclareRobustCommand\citet
+   {\NAT@swafalse
+         \@ifstar{\NAT@fulltrue\NAT@citet}{\NAT@fullfalse\NAT@citet}}
+\newcommand\NAT@citet{\@ifnextchar[{\NAT@@citet}{\NAT@@citet[]}}
+\newcommand\NAT@@citet{}
+\def\NAT@@citet[#1]{\@ifnextchar[{\NAT@@@citet[#1]}{\NAT@@@citet[][#1]}}
+\newcommand\NAT@@@citet{}
+\def\NAT@@@citet[#1][#2]#3{%
+%<!subpack>  \ifNAT@numbers\ifNAT@full\citefullauthor{#3}\else
+%<!subpack>  \citeauthor{#3}\fi\ \fi
+  \@citex[#1][#2]{#3}}
+%    \end{macrocode}
+% This command can only handle single keys (in numerical mode).
+% \end{macro}
+% 
+% \begin{macro}{\citep}
+% \changes{5.5}{1995 Mar 27}{Add macro as shorthand for \cs{cite[]}}
+% \changes{6.5}{1997 Jan 30}{Make this standard parenthetical citation, 
+%        with notes}
+% Parenthetical citations are made with the |\citep| command, which has a 
+% starred
+% form for full authors, and may have one or two optional arguments for notes.
+%
+% This command was originally added by special request to be a simplification
+% for |\cite[]|\marg{key}, and I added it grudgingly. After I reprogrammed 
+% \thestyle\ to handle author--year and numerical citations with the same
+% \texttt{.bst} file, I needed to add the |\citet| command, and this one
+% became an obvious companion for parenthetical citations. I have now altered
+% its coding to be the standard, being fully equivalent in functionality
+% to the older syntax |\cite|\oarg{pre}\oarg{post}\marg{key}.
+%    \begin{macrocode}
+%<209>\renewcommand\citep
+%<!209>\DeclareRobustCommand\citep
+   {\NAT@swatrue
+         \@ifstar{\NAT@fulltrue\NAT@citep}{\NAT@fullfalse\NAT@citep}}
+\newcommand\NAT@citep{\@ifnextchar[{\NAT@@citep}{\NAT@@citep[]}}
+\newcommand\NAT@@citep{}
+\def\NAT@@citep[#1]{\@ifnextchar [{\@citex[#1]}{\@citex[][#1]}}
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\cite}
+% \changes{5.0}{1994 May 18}{Add a second optional argument.}
+% \changes{5.3}{1994 Sep 19}{Add starred version to print full author list.}
+% \changes{5.4}{1994 Nov 24}{Replace \cmd{\if@tempswa} with \cmd{\ifNAT@swa}.}
+% \changes{6.5}{1997 Jan 30}{Declare obsolete, retained for compatibility}
+% The |\cite| command was originally used to produce both textual and
+% parenthetical citations; with an option argument, even an empty one,
+% the citation was parenthical. I now recommend the use of |\citet| and 
+% |\citep| instead, retaining |\cite| only for compatibility.
+%
+% It is equivalent to |\citep| in numerical mode, so it can in fact be 
+% used as standard \LaTeX\ syntax with numerical citations.
+%    \begin{macrocode}
+%<209>\renewcommand\cite
+%<!209>\DeclareRobustCommand\cite
+    {\@ifstar{\NAT@fulltrue\NAT@cites}{\NAT@fullfalse\NAT@cites}}
+\newcommand\NAT@cites{\@ifnextchar [{\NAT@swatrue\NAT@@citep}{\NAT@swafalse
+    \NAT@@citep[]}}
+% \end{macro}
+% 
+% \begin{macro}{\citealt}
+% \changes{5.5}{1995 Mar 16}{Add macro}
+% \changes{6.5}{1997 Jan 30}{Uses \cs{citet} instead of \cs{cite}}
+% An alternative form of citation is one in which the parentheses are not
+% printed. Since the effect of this command is exactly the same as the
+% regular |\citet| but with |\NAT@open| and |\NAT@close| set to blank,
+% define it just in that way. The starred version for full authors can be
+% retained. Notes are not possible, and would be unnecessary without braces.
+% 
+% This form has been added at the request of Alexander Holt, who wishes to
+% be able to print all three flavours: parenthetical, textual with
+% parentheses, and textual without. The |\citealt| command must be able to
+% handle multiple references and use the same punctuation scheme as
+% |\citet|. 
+% 
+% By defining |\citealt| in terms of |\citet|, not only do I save
+% considerable programming effort, but David Carlisle's \texttt{showkeys}
+% package will work with this command too.
+%    \begin{macrocode}
+%<*!subpack>
+%<209>\renewcommand\citealt
+%<!209>\DeclareRobustCommand\citealt
+    {\@ifstar{\NAT@alts}{\NAT@alt}}
+\newcommand\NAT@alt[1]{{\ifNAT@numbers\else
+     \renewcommand\NAT@open{}\renewcommand\NAT@close{}\fi\cite{#1}}}
+\newcommand\NAT@alts[1]{{\ifNAT@numbers\else
+     \renewcommand\NAT@open{}\renewcommand\NAT@close{}\fi\cite*{#1}}}
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citeauthor}
+% \changes{5.0}{1994 May 18}{Add means to cite authors only.}
+% \changes{5.2}{1994 Aug 25}{Enclose \cs{@citenm} in braces.}
+% \changes{5.2}{1994 Aug 25}{Add auxiliary file entry.}
+% \changes{6.0}{1995 Sep 4}{Check for empty author}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% \begin{macro}{\citeyear}
+% \changes{5.0}{1994 May 18}{Add means to cite year only.}
+% \changes{5.2}{1994 Aug 25}{Add auxiliary file entry.}
+% \changes{6.0}{1995 Sep 4}{Check for empty year}
+% \changes{6.4}{1996 Sep 12}{Extra letter also printed with year number}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% In an author--year scheme, it is sometimes necessary to refer to the
+% authors of a work without the year. It might even be necessary to refer
+% to the year alone, but I can hardly imagine that. Both possibilities are
+% allowed for here.
+%    \begin{macrocode}
+\newcommand\citeauthor[1]{\if@filesw\immediate\write
+     \@auxout{\string\citation{#1}}\fi
+     \@ifundefined{b@#1\@extra@b@citeb}{%
+%<209>       {\reset@font\bf ?}\@warning
+%<!209>       {\reset@font\bfseries ?}\NAT@citeundefined
+%<!209>            \PackageWarning{natbib}%
+       {Citation `#1' on page \thepage \space undefined}}%
+       {\NAT@parse{#1}\ifx\NAT@noname\NAT@name
+%<209>         {\reset@font\bf(author?)}\@warning
+%<!209>         {\reset@font\bfseries(author?)}\PackageWarning{natbib}
+           {Author undefined for citation `#1' 
+%<209>              ^^J
+%<!209>             \MessageBreak       
+            on page \thepage}\else
+         {\hyper@natlinkstart{#1}\NAT@name\hyper@natlinkend}\fi}%
+}
+\newcommand\citeyear[1]{\if@filesw\immediate\write
+     \@auxout{\string\citation{#1}}\fi
+     \@ifundefined{b@#1\@extra@b@citeb}{%
+%<209>       {\reset@font\bf ?}\@warning
+%<!209>       {\reset@font\bfseries ?}\NAT@citeundefined
+%<!209>            \PackageWarning{natbib}%
+       {Citation `#1' on page \thepage \space undefined}}%
+       {\NAT@parse{#1}\if\relax\NAT@date\relax
+%<209>         {\reset@font\bf(year?)}\@warning
+%<!209>         {\reset@font\bfseries(year?)}\PackageWarning{natbib}
+           {Year undefined for citation `#1' 
+%<209>              ^^J
+%<!209>             \MessageBreak       
+            on page \thepage}\else
+         {\hyper@natlinkstart{#1}\NAT@date\hyper@natlinkend}\fi}%
+}
+%    \end{macrocode}
+% \end{macro}\end{macro}
+% 
+% \begin{macro}{\citefullauthor}
+% \changes{5.3}{1994 Sep 13}{Add macro for those bib styles with full author
+%     list available}
+% \changes{6.0}{1995 Sep 4}{Check for empty author}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% Some of the author--year bibliography styles supported here (\texttt{harvard}
+%   and \texttt{newapa}) allow a citation with the full author list, because
+%   they have the necessary information in the |\bibitem| entry. With 
+%   version~5.3, I change the native form of this entry to allow
+%   full authors too.
+%
+% Since I now have a starred form of |\cite| for the full author list, it
+%  might be reasonable to use a starred |\citeauthor| instead of
+% |\citefullauthor|. However, that will conflict with the provisions for
+% \thestyle{} to be found in Carlisle's \texttt{showkeys} package. That's life.
+%    \begin{macrocode}
+\newcommand\citefullauthor[1]{\if@filesw\immediate\write
+     \@auxout{\string\citation{#1}}\fi
+     \@ifundefined{b@#1\@extra@b@citeb}{%
+%<209>       {\reset@font\bf ?}\@warning
+%<!209>       {\reset@font\bfseries ?}\NAT@citeundefined
+%<!209>            \PackageWarning{natbib}%
+       {Citation `#1' on page \thepage \space undefined}}%
+       {\NAT@parse{#1}\ifx\NAT@noname\NAT@all@names
+%<209>         {\reset@font\bf(author?)}\@warning
+%<!209>         {\reset@font\bfseries(author?)}\PackageWarning{natbib}
+           {Author undefined for citation `#1' 
+%<209>              ^^J
+%<!209>             \MessageBreak       
+            on page \thepage}\else
+         {\hyper@natlinkstart{#1}\NAT@all@names\hyper@natlinkend}\fi}%
+}
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Parsing the Author--Year Entries}
+% \begin{macro}{\NAT@parse}
+% \changes{5.0}{1994 May 18}{Add parsing command, with additional 
+%    font and sub-accent commands relaxed}
+% \changes{5.1}{1994 Jun 22}{For \LaTeXe{} of \texttt{1994/06/01}, 
+%    can protect font and sub-accents much better}
+% \changes{5.2}{1994 Aug 24}{2.09 version to run in compatibility mode}
+% \changes{5.3}{1994 Sep 13}{Add full author list}
+% \changes{5.3}{1994 Sep 19}{Support starred version of \cs{cite} for full
+%    author list}
+% \changes{5.3}{1994 Sep 26}{Use \cs{@unexpandable@protect} in place of
+%    \cs{noexpand}}
+% \changes{5.4}{1995 Feb 6}{Call \cs{@parse@date} to split date into year and
+%     extra label}
+% \changes{5.5}{1995 May 18}{Rename from \cs{@cite@parse}}
+% \changes{6.0}{1995 Sep 4}{Remove \cs{relax} from expanded \cs{@tempa}
+%    definition; no longer needed under new system}
+% \changes{6.0}{1995 Sep 21}{Prevent expansion of forced space (tilde)}
+% The |\bibcite| commands in the auxiliary file associate the numerical and
+% author--year information with the |\bibitem| key, which is the argument to
+% |\NAT@parse|. As of version~6.0, the information is stored in
+% |\b@|\emph{key} for each citation, as four separate items.
+% \begin{quote}\begin{tabular}{lll}
+%   1. & |\NAT@num| & sequence number or non-author--year label \\
+%   2. & |\NAT@date| & year, with possible extra label \\
+%   3. & |\NAT@name| & short author list \\
+%   4. & |\NAT@all@names| & long author list (optional) 
+% \end{tabular}\end{quote}
+% In order to define each of the above commands as the appropriate item, it
+% is first necessary to expand |\b@|\emph{key} into a temporary command
+% |\NAT@temp|, which is then used as the argument of |\NAT@split|, which
+% makes the individual assignments.
+% 
+%    \begin{macrocode}
+\newcommand\NAT@parse[1]{{%
+%<*209>
+      \@ifundefined{documentclass}
+       {\let\prm=\relax\let\psf=\relax\let\ptt=\relax\let\pbf=\relax
+        \let\psl=\relax\let\psc=\relax\let\pit=\relax\let\pem=\relax
+        \let\prmfamily=\relax\let\psffamily=\relax\let\pttfamily=\relax
+        \let\pbfseries=\relax\let\pslshape=\relax\let\pscshape=\relax
+        \let\pitshape=\relax\let\pmdseries=\relax\let\pupshape=\relax
+        \let\pc=\relax \let\pd=\relax \let\pb=\relax}
+       {\let\protect=\@unexpandable@protect\let~\relax}%
+%</209>
+%<!209>     \let\protect=\@unexpandable@protect\let~\relax
+     \xdef\NAT@temp{\csname b@#1\@extra@b@citeb\endcsname}}%
+     \expandafter\NAT@split\NAT@temp
+     \expandafter\NAT@parse@date\NAT@date??????@@%
+%<!subpack&!209>     \ifciteindex\NAT@index\fi
+}
+%    \end{macrocode}
+% Some further notes on the above: for 2.09 it is necessary to turn off all the
+% protected font commands |\prm| etc.\ when the label text is expanded into
+% |\NAT@temp|, for otherwise there will be problems with the New Font
+% Selection Scheme (NFSS); the protected sub-accent commands (protected
+% versions of |\c|, |\d|, and |\b|) also cause troubles on expansion.
+% Admittedly, this is not a good solution, for the list of problem commands
+% might be much longer, but for the meantime, this will have to do.
+% 
+% For \LaTeXe, at least after the official release of
+% \texttt{1994/06/01}, commands are made robust in a totally different
+% manner, no longer by adding a \texttt{p} in front, but by adding a space
+% afterwards. This means the commands in the auxiliary files look like the
+% protected version once again, and not raw commands. They are infinitely
+% protected. The above problem is easily overcome by making |\protect|
+% equal to |\@unexpandable@protect|. A definitive list of commands to 
+% protect is no longer necessary. (Initially I used |\noexpand|, but
+% that only worked for font commands, not accents. Reading the documentation
+% in \texttt{ltdefns.dtx} indicated that this is the better redefinition
+% of |\protect|.)
+%
+% This trick is also applied to the 2.09 version for when it is running
+% in the compatibility mode of \LaTeXe. This is needed for the 
+% journal-specific coding, more than for the normal package.
+% 
+% The automatic indexing of citations (|\NAT@index|) is described in
+% Section~\ref{sec:idx}.
+% 
+% \end{macro}
+% 
+% \begin{macro}{\NAT@split}
+% \changes{5.3}{1994 Sep 13}{Changed to support full author list}
+% \changes{5.5}{1995 May 14}{Fix coding slightly}
+% \changes{5.5}{1995 May 18}{Renamed from \cs{@citez}}
+% \changes{6.0}{1995 Sep 4}{Recode for new \cs{bibcite} structure}
+% The actual assignments of the author--year and numerical label texts to
+% the corresponding commands is carried out by |\NAT@split|. If the long
+% author list is missing (argument |#4|), it is set equal to the short
+% list.
+%    \begin{macrocode}
+\newcommand\NAT@split[4]{%
+  \gdef\NAT@num{#1}\gdef\NAT@name{#3}\gdef\NAT@date{#2}%
+  \gdef\NAT@all@names{#4}%
+  \ifx\NAT@noname\NAT@all@names \gdef\NAT@all@names{#3}\fi}
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\NAT@parse@date}
+% \changes{5.4}{1995 Feb 6}{Add macro to split date into year and extra label}
+% \changes{5.5}{1995 Mar 24}{Put extra label in braces to localize any font
+%      changes}
+% \changes{5.5}{1995 May 18}{Rename from \cs{@parse@date}}
+% With version 5.4, add the macro |\NAT@parse@date| that splits the date up
+% into year and extra label, putting them into |\NAT@year| and |\NAT@exlab|.
+% This is used to test if authors and years are equal for two adjacent
+% citations, in which case, only the extra label is printed. The 
+% macro searches the first 4 characters of the date for a letter 
+% (|\catcode|=11) which then becomes the extra label. If there are only
+% numerals in the first 4 positions (more precisely, non-letters), the 5th
+% character is taken as extra label. If there is none, this will be a 
+% question mark.
+%    \begin{macrocode}
+\newcommand\NAT@parse@date{}
+\def\NAT@parse@date#1#2#3#4#5#6@@{%
+  \ifnum\the\catcode`#1=11\def\NAT@year{}\def\NAT@exlab{#1}\else
+  \ifnum\the\catcode`#2=11\def\NAT@year{#1}\def\NAT@exlab{#2}\else
+  \ifnum\the\catcode`#3=11\def\NAT@year{#1#2}\def\NAT@exlab{#3}\else
+  \ifnum\the\catcode`#4=11\def\NAT@year{#1#2#3}\def\NAT@exlab{#4}\else
+    \def\NAT@year{#1#2#3#4}\def\NAT@exlab{{#5}}\fi\fi\fi\fi}
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Automatic Index Entries for Citations}\label{sec:idx}
+% 
+% \begin{macro}{\NAT@idxtxt}
+% \changes{6.0}{1995 Sep 21}{Add macro}
+% \begin{macro}{\NAT@index}
+% \changes{6.0}{1995 Sep 21}{Add macro}
+% To make an entry in the index for every citation, I have added
+% |\NAT@index| to the |\NAT@parse| command. This will do nothing unless
+% |\makeindex| has been issued in the preamble, in which case it writes the
+% citation information to the \texttt{.idx} file by means of the standard
+% \LaTeX\ internal |\@wrindex|. The actual format of the citation
+% information is contained in |\NAT@idxtxt| which a user may redefine if
+% needed.
+%    \begin{macrocode}
+%<*!subpack&!209>
+\newcommand\NAT@index{}
+\let\NAT@makeindex=\makeindex
+\renewcommand\makeindex{\NAT@makeindex
+  \renewcommand\NAT@index{\@bsphack\begingroup
+     \def~{\string~}\@wrindex{\NAT@idxtxt}}}
+\newcommand\NAT@idxtxt{\NAT@name\ \NAT@open\NAT@date\NAT@close}
+%    \end{macrocode}
+% \end{macro}\end{macro}
+% \begin{macro}{\ifciteindex}
+% \changes{6.0}{1995 Sep 21}{Add flag}
+% The switch for activating automatic citation indexing is defined here.
+%    \begin{macrocode}
+\newif\ifciteindex \citeindexfalse
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\citeindextype}
+% \changes{6.0}{1995 Sep 29}{Add macro}
+% \begin{macro}{\NAT@index@alt}
+% \changes{6.0}{1995 Sep 29}{Add macro}
+% The above coding will not work with the package \texttt{index.sty} by
+% David~M. Jones. For that package, an alternative definition of |\NAT@index|
+% is needed which is activated at the beginning of the document if
+% \texttt{index} has been loaded. It thus does not matter in which order
+% \thestyle\ or \texttt{index} are loaded.
+% 
+% With the \texttt{index} package, it is possible to have several index
+% files, defined by a |\newindex| command that associates a name with two
+% file extensions. By default, the name \texttt{default} is associated with
+% \texttt{.idx} and \texttt{.ind}. To make the automatic index entries go to
+% a different set, redefine |\citeindextype|.
+% 
+%    \begin{macrocode}
+\newcommand\citeindextype{default}
+\newcommand\NAT@index@alt{{\let\protect=\noexpand\let~\relax
+  \xdef\NAT@temp{\NAT@idxtxt}}\expandafter\NAT@exp\NAT@temp\@nil}
+\newcommand\NAT@exp{}
+\def\NAT@exp#1\@nil{\index[\citeindextype]{#1}}
+
+\AtBeginDocument{%
+\@ifpackageloaded{index}{\let\NAT@index=\NAT@index@alt}{}}
+%</!subpack&!209>
+%    \end{macrocode}
+% \end{macro}\end{macro}
+% 
+% \subsection{Writing the Entries to the Auxiliary File}
+% 
+% \noindent(New to version 6.0.)
+%
+% The author--year information is transferred from the \btx{} database to
+% the document via |\bibitem| commands in the |thebibliography|
+% environment. Standard \LaTeX\ simply assigns a running number to these
+% entries, and writes that number with the citation key to the auxiliary
+% file. For author--year citations, the author list and year must be written
+% somehow to the auxiliary file. The form for this is to be
+% \begin{quote}
+% |\bibcite|\marg{key}|{|\marg{num}\marg{year}\marg{short}\marg{long}|}|
+% \end{quote}
+% This is the same form as in standard \LaTeX, except that the second
+% argument becomes a set of 4 items. Here \emph{num} is the sequential
+% number that is to be used if a numerical style is selected, \emph{short}
+% is the abbreviate author list (Jones et al.), \emph{long} the full author
+% list.
+% 
+% The author--year information is contained in the optional argument to
+% |\bibitem|, but just how it is formatted depends on the system used. The
+% native \thestyle\ syntax is
+% \begin{quote}
+% |\bibitem[|\emph{short}|(|\emph{year}|)|\emph{long}|]|\marg{key}
+% \end{quote}
+% while the \texttt{chicago} system is
+% \begin{quote}
+% |\bibitem[\protect\citeauthoryear|\marg{long}\marg{short}\marg{year}|]|%
+%   \marg{key}
+% \end{quote}
+% 
+% \begin{macro}{\NAT@ifcmd}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% \begin{macro}{\NAT@ifxcmd}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% It is necessary to process the optional argument by first testing if it
+% contains a command, and if so, to execute that command. Otherwise, insert
+% our own command to process the following text.
+%    \begin{macrocode}
+\newcommand\NAT@ifcmd{\futurelet\NAT@temp\NAT@ifxcmd}
+\newcommand\NAT@ifxcmd{\ifx\NAT@temp\relax\else\expandafter\NAT@bare\fi}
+%    \end{macrocode}
+% This actually only tests if the next token expands to |\relax|, which is
+% what |\protect| will be at this point. If so, just procede: the command
+% itself follows. Otherwise, insert |\NAT@bare|. (Note, we must also define
+% the possible commands like |\citeauthoryear| to do what we want.)
+% \end{macro}\end{macro}
+% 
+% \begin{macro}{\NAT@bare}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% The command that is inserted if none is present must parse the native
+% syntax for the author--year information. The template is somewhat complex
+% because it must be able to test if there are no parentheses at all, in
+% which case it activates the alternative, |\NAT@apalk| for the
+% \texttt{apalike} syntax. When |\NAT@ifcmd| is invoked, it adds
+% |()()\@nil| in order to provide the full template of |\NAT@bare|; if the
+% argument itself contains no text in parentheses (not \thestyle{}
+% syntax) then |#2| will be empty; otherwise, |#4| catches the extra 
+% parentheses.
+%    \begin{macrocode}
+\def\NAT@bare#1(#2)#3()#4\@nil#5{%
+%<*all|apalike|authordate>
+  \if\relax#2\relax
+  \expandafter\NAT@apalk#1, , \@nil{#5}\else
+  \stepcounter{NAT@ctr}%
+%</all|apalike|authordate>
+  \NAT@wrout{\arabic {NAT@ctr}}{#2}{#1}{#3}{#5}
+%<all|apalike|authordate>\fi
+}
+%    \end{macrocode}
+% The |NAT@ctr| above contains the designation of whatever counter is
+% selected in the list environment for the \texttt{thebibliography}; it is
+% the sequential counter for the entries.
+% \end{macro}
+%
+% \begin{macro}{\NAT@wrout}
+% \changes{6.0}{1995 Sep 4}{Add macro}
+% \begin{macro}{\NAT@noname}
+% \changes{6.0}{1995 Sep 6}{Add macro}
+% \changes{6.0}{1995 Sep 21}{Prevent expansion of forced space (tilde)}
+% Write the information to the auxiliary file as two arguments to |\bibcite|.
+% 
+% Note: the 5 arguments are: counter, year, short list, long list, key.
+% The two author lists are written enclosed in braces to make sure any
+% font commands are kept local. Otherwise, one level of braces disappears for
+% authors like |{\em Jones}|.
+%
+% To test later for the absence of names, define |\NAT@noname| here.
+% Define it with |\def|, otherwise it will be `long' and will not test
+% correctly with |\NAT@all@names| which is defined with |\gdef|.
+%    \begin{macrocode}
+\newcommand\NAT@wrout[5]{%
+\if@filesw
+      {\let\protect\noexpand\let~\relax
+       \immediate
+       \write\@auxout{\string\bibcite{#5}{{#1}{#2}{{#3}}{{#4}}}}}\fi
+\ignorespaces}
+\def\NAT@noname{{}}
+%    \end{macrocode}
+% \end{macro}\end{macro}
+% 
+% \begin{macro}{\bibitem}
+% \changes{6.0}{1995 Sep 4}{Recode from standard}
+% \begin{macro}{\@lbibitem}
+% \changes{6.0}{1995 Sep 4}{Recode from standard}
+% \changes{6.4}{1996 Oct 2}{Add dummy macros for \texttt{hyperref.sty}}
+% The above commands are initiated with |\NAT@ifcmd| which decides whether
+% |\NAT@bare| or one of the other commands is to be executed on the
+% following arguments. It is actually |\@lbibitem| that calls |\NAT@ifcmd|,
+% which in turn is invoked by the user command |\bibitem|.
+% 
+% If |\bibitem| has no optional argument, then we have a numerical citation
+% style, which is to be forced by setting |\NAT@stdbst|. Put the sequential
+% counter value in as the argument to |\@lbibitem| which is then treated as
+% a non-author--year label.
+%    \begin{macrocode}
+\renewcommand\bibitem{%
+  \@ifnextchar[{\@lbibitem}{%
+%<!subpack>    \global\NAT@stdbsttrue
+    \stepcounter{NAT@ctr}\@lbibitem[\arabic{NAT@ctr}]}}
+%    \end{macrocode}
+% Write the label with |\item| in the bibliography listing with the current
+% value of |\NAT@num|, if it exists. This will either be the sequential
+% number or whatever non-author--year text that was given as a special
+% `numerical'. Since |\@biblabel| outputs only in numerical mode, this
+% label vanishes for author--year mode.
+% 
+% Finally invoke |\NAT@ifcmd| with the funny template to activate
+% |\NAT@bare| or some alternative.
+%    \begin{macrocode}
+\def\@lbibitem[#1]#2{%
+   \@ifundefined{b@#2\@extra@b@citeb}{\def\NAT@num{}}{\NAT@parse{#2}}%
+   \item[\hfil\hyper@natanchorstart{#2}\@biblabel{\NAT@num}%
+    \hyper@natanchorend]%
+    \NAT@ifcmd#1()()\@nil{#2}}
+%    \end{macrocode}
+% Note: in standard \LaTeX, the sequential list counter is printed directly
+% with |\item|, and then written to the auxiliary file so that |\cite| can
+% refer to it on the next run. Here, |\item| prints exactly the same thing
+% as |\cite| on the current run, if we are in numerical mode, otherwise
+% nothing.
+%
+% \changes{6.3}{1996 Jun 10}{Include \texttt{showkeys} coding if already
+%               loaded}
+% \changes{6.4}{1996 Jun 27}{Remove from 2.09 coding}
+% If the \texttt{showkeys} package has already been loaded, the revised
+% version of |\@lbibitem| will not have been saved. In this case, rerun some
+% of the coding from that package. (If \texttt{showkeys} is loaded after
+% \thestyle, there is no problem.)
+%    \begin{macrocode}
+%<*!209>
+\@ifpackageloaded{showkeys}{%
+   \let\SK@lbibitem\@lbibitem
+   \def\@lbibitem[#1]#2{%
+     \SK@lbibitem[#1]{#2}\SK@\SK@@label{#2}\ignorespaces}}{}
+%</!209>
+%    \end{macrocode}
+% \end{macro}\end{macro}
+% 
+% \begin{macro}{\ifNAT@stdbst}
+% \changes{6.0}{1995 Sep 4}{Add flag}
+% If any non-author--year |\bibitem|s have been issued, then force
+% numerical mode, since the author--year |\bibitem|s can handle this, but
+% the numerical ones cannot work in author--year mode. Do this by inserting
+% |\NAT@numberstrue| in the auxiliary file.
+%    \begin{macrocode}
+%<*!subpack>
+\newif\ifNAT@stdbst \NAT@stdbstfalse
+
+%<209>\let\NAT@enddoc=\enddocument
+%<209>\def\enddocument
+%<!209>\AtEndDocument
+  {\ifNAT@stdbst\if@filesw\immediate\write\@auxout{\string
+   \global\string\NAT@numberstrue}\fi\fi
+%<209>\NAT@enddoc
+  }
+%</!subpack>
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\bibcite}
+% \changes{6.1}{1995 Dec 5}{Add own coding for this macro}
+% \changes{6.1a}{1995 Dec 19}{Add own test for changed citations}
+% Not wanting to rely on the coding for |\bibcite| in the kernel, I define
+% it myself. It is not enough just to `provide' it, for it must do the 
+% right thing: write a label named |\b@|\emph{key}. The \LaTeX3 boys
+% might decide to keep the command, but have it store the citations with
+% a different prefix.
+% 
+% (I outsmarted myself here again. The test for changed citations and
+% references involves reading in the auxiliary file with revised
+% definitions for |\label| and |\bibcite|. The December~1995 release does
+% this via a generalized labelling command |\@newl@bel|. As a result, I
+% must add this test myself. Not so bad, because the warning comes from
+% \thestyle\ and explicitly refers to citations instead of just
+% `references'.)
+%    \begin{macrocode}
+%<*!209>
+\providecommand\bibcite{}
+\renewcommand\bibcite[2]{\@ifundefined{b@#1\@extra@binfo}\relax
+     {\NAT@citemultiple
+      \PackageWarningNoLine{natbib}{Citation `#1' multiply defined}}%
+  \global\@namedef{b@#1\@extra@binfo}{#2}}
+\AtEndDocument{\NAT@swatrue\renewcommand\bibcite[2]%
+                         {\NAT@testdef{#1}{#2}}}
+\newcommand\NAT@testdef[2]{%
+  \def\NAT@temp{#2}\expandafter \ifx \csname b@#1\@extra@binfo\endcsname
+    \NAT@temp \else \ifNAT@swa \NAT@swafalse
+       \PackageWarningNoLine{natbib}{Citation(s) may have
+          changed.\MessageBreak
+          Rerun to get citations correct}\fi\fi}
+%</!209>
+%<209>\renewcommand\bibcite[2]{\global\@namedef{b@#1\@extra@binfo}{#2}}
+%    \end{macrocode}
+% \end{macro}
+% 
+% \subsection{Other Author--Year Schemes}
+% \begin{macro}{\NAT@apalk}
+% \changes{4.1}{1993 Oct 4}{Simplify by using comma-space as separator}
+% \changes{5.3}{1994 Sep 13}{Full author list equals short list}
+% \changes{5.5}{1995 May 18}{Renamed from \cs{@citeapalk}}
+% \changes{6.0}{1995 Sep 4}{Recoded for version~6.0}
+% If the argument of |\bibitem| contains no command, and if it does not
+% conform to the \thestyle{} syntax, then try the \texttt{apalike}
+% syntax (\emph{short}\texttt{, }\emph{year}). This has a funny template
+% too in order to test for different syntax, which is indicated when |#2|
+% is empty. In this case, give up trying to fit it to author--year formats,
+% and go over to `numerical' with a special label. Set the flag
+% |\NAT@stdbst| to mark this. This forces a numerical citation style.
+%    \begin{macrocode}
+%<*all|apalike|authordate>
+\newcommand\NAT@apalk{}
+\def\NAT@apalk#1, #2, #3\@nil#4{\if\relax#2\relax
+%<!subpack>  \global\NAT@stdbsttrue
+  \NAT@wrout{#1}{}{}{}{#4}\else
+  \stepcounter{NAT@ctr}%
+  \NAT@wrout{\arabic {NAT@ctr}}{#2}{#1}{}{#4}\fi}
+%</all|apalike|authordate>
+%    \end{macrocode}
+% Note: the |NAT@ctr| is stepped here and everywhere else it is used,
+% except when a special `numerical' label is being used. This conforms to
+% standard \LaTeX\ which only increments the counter for pure numerical
+% labels, without an optional argument to |\bibitem|.
+% \end{macro}
+% 
+% The other schemes of citation labelling may also be accommodated, more
+% easily than \texttt{apalike}. It is just necessary to define the particular
+% commands, like |\citeauthoryear| to write the arguments to the
+% auxiliary file in the required. These commands are detected by
+% |\NAT@ifcmd| and simply left to be executed.
+% 
+% The only complication is that |\citeauthoryear| may be given with two or
+% three arguments. This is accommodated by testing the |#3| and changing
+% the form of the write command accordingly.
+% 
+% The form of the template is the same as for |\NAT@bare|, since this
+% command is inserted in its place and must therefore conform to its
+% syntax.
+% 
+% \begin{macro}{\citeauthoryear}
+% \changes{5.3}{1994 Sep 13}{Allow full authors in citation}
+% \changes{6.0}{1995 Sep 4}{Recode for version 6.0}
+% For \texttt{newapa.bst} itself, the commands |\citestarts|, |\citeends|,
+% as well as |\betweenauthors| must be defined; for others in this group,
+% these commands are not needed.
+%    \begin{macrocode}
+%<*newapa|chicago|all>
+\newcommand\citeauthoryear{}
+\def\citeauthoryear#1#2#3()()\@nil#4{\stepcounter{NAT@ctr}\if\relax#3\relax
+   \NAT@wrout{\arabic {NAT@ctr}}{#2}{#1}{}{#4}\else
+   \NAT@wrout{\arabic {NAT@ctr}}{#3}{#2}{#1}{#4}\fi}
+\newcommand\citestarts{\NAT@open}
+\newcommand\citeends{\NAT@close}
+\newcommand\betweenauthors{and}
+%</newapa|chicago|all>
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\astroncite}
+% \changes{6.0}{1995 Sep 4}{Recode for version 6.0}
+% The |\astroncite| command must similarly conform to |\NAT@bare| syntax
+% and put its arguments into the auxiliary file in the correct order.
+%    \begin{macrocode}
+%<*astron|all>
+\newcommand\astroncite{}
+\def\astroncite#1#2()()\@nil#3{\stepcounter{NAT@ctr}\NAT@wrout{\arabic
+{NAT@ctr}}{#2}{#1}{}{#3}}
+%</astron|all>
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\citename}
+% \changes{6.0}{1995 Sep 4}{Recode for version 6.0}
+% The |\citename| command just converts its arguments to the |\NAT@apalk|
+% syntax, since its first argument should end in \verb*!, ! as for
+% \texttt{apalike}. By making use of |\NAT@apalk| here, it is also possible
+% to check for non-conformity of the syntax.
+%    \begin{macrocode}
+%<*authordate|all>
+\newcommand\citename{}
+\def\citename#1#2()()\@nil#3{\expandafter\NAT@apalk#1#2, \@nil{#3}}
+%</authordate|all>
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\harvarditem}
+% \changes{5.3}{1994 Sep 13}{Allow full authors in citation}
+% \changes{5.5}{1995 May 18}{Defined in \LaTeXe\ terms}
+% The Harvard family is allowed for simply by defining |\harvarditem| in
+% terms of |\bibitem| with the \thestyle{} form.
+% 
+% The |\harvarditem| must allow for the optional argument, which is 
+% the short author list. Use the short list in |\bibitem| if it is there,
+% otherwise the long list must be taken.
+% 
+%    \begin{macrocode}
+%<*harvard|all>
+%<!209>\newcommand\harvarditem[4][]%
+%<209>\def\harvarditem{\@ifnextchar[{\@harvarditem}{\@harvarditem[]}}
+%<209>\def\@harvarditem[#1]#2#3#4%
+    {\if\relax#1\relax\bibitem[#2(#3)]{#4}\else
+        \bibitem[#1(#3)#2]{#4}\fi }
+%    \end{macrocode}
+% The command |\citeasnoun| must be defined since \texttt{harvard.bst}
+% can add it for cross-referencing.
+% \end{macro}
+%
+% \begin{macro}{\harvardleft}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardright}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardyearleft}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardyearright}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardand}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% \begin{macro}{\harvardurl}
+% \changes{5.3}{1994 Sep 13}{Add macro}
+% The \texttt{harvard} package has been updated for \LaTeXe, and includes
+% some new punctuation commands in the accompanying \texttt{bst} files.
+% (Maybe they were always there and I overlooked them.) In order for
+% \thestyle{} to work with these, it needs to define them. The |left| and 
+% |right| commands have equivalents already; |\harvardurl| is defined
+% as in \texttt{harvard.sty}. It is necessary to define |\harvardand|
+% conditionally, and only later, in case it has already been set to
+% something else by a |\bibstyle@xxx| (e.g., \texttt{agsm} sets it
+% to |\&|.)
+%    \begin{macrocode}
+\newcommand\harvardleft{\NAT@open}
+\newcommand\harvardright{\NAT@close}
+\newcommand\harvardyearleft{\NAT@open}
+\newcommand\harvardyearright{\NAT@close}
+%<!209>\AtBeginDocument{\providecommand{\harvardand}{and}}
+%<209>\def\harvardand{and}
+\newcommand\harvardurl[1]{\textbf{URL:} \textit{##1}}
+%</harvard|all>
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}\end{macro}\end{macro}
+%
+% \subsection{The Bibliography Listing}
+% Changes must be made to the \texttt{thebibliography} environment for
+% author--year citations. This is done be defining the environment with the
+% features common to both schemes, and then by invoking |\@bibsetup|, which
+% is either the author--year or numerical version.
+% 
+% \begin{macro}{\bibsection}
+% \changes{4.2}{1993 Oct 22}{Make specific for JGR, GRL, NLINPROC}
+% \changes{5.5}{1995 May 18}{Use \cs{renewcommand}}
+% \changes{6.2}{1996 Apr 15}{Modified for \texttt{amsart} and \texttt{amsbook}}
+% \changes{6.4}{1996 Sep 1}{Modified for \texttt{sectionbib} option}
+% \changes{6.5}{1997 Feb 5}{Allow for \cs{bib@headings} in KOMA scripts}
+% First, |\bibsection| is defined according to the main style: if chapters
+% exist, then the bibliography is a numberless chapter, otherwise a
+% numberless section. For the specific journals, |\bibsection| takes on
+% special definitions.
+% 
+% Since the AMS classes \texttt{amsart} and \texttt{amsbook} redefine
+% |\section*| in a way that is incompatible with the way it is used in 
+% the \texttt{bibliographystyle} environment, it is necessary to remove the
+% |\@mkboth| from the section title. Since these classes do not use this
+% command at this point, there is no loss of functionality.
+%
+% The packages of the KOMA scripts make use of |\bib@heading| which functions
+% much like |\bibsection|. If it is defined, let |\bibsection| be equal to it.
+%    \begin{macrocode}
+%<*!agu&!egs>
+%<!209>\providecommand\bibsection{}
+%<209>\def\bibsection{}
+\@ifundefined{chapter}%
+  {\renewcommand\bibsection{\section*{\refname
+    \@mkboth{\MakeUppercase{\refname}}{\MakeUppercase{\refname}}}}}
+  {\@ifundefined{NAT@sectionbib}%
+    {\renewcommand\bibsection{\chapter*{\bibname
+     \@mkboth{\MakeUppercase{\bibname}}{\MakeUppercase{\bibname}}}}}
+    {\renewcommand\bibsection{\section*{\bibname
+     \ifx\@mkboth\@gobbletwo\else\markright{\MakeUppercase{\bibname}}\fi}}}}
+%<*!subpack>
+%<*!209>
+\@ifclassloaded{amsart}%
+  {\renewcommand\bibsection{\section*{\refname}}{}}{}
+\@ifclassloaded{amsbook}%
+  {\renewcommand\bibsection{\section*{\bibname}}{}}{}
+%</!209>
+\@ifundefined{bib@heading}{}{\let\bibsection\bib@heading}
+%</!subpack>
+%</!agu&!egs>
+%<egs>\def\bibsection{\if@draft\newpage\fi
+%<egs>    \noappendix\section*{\refname}}
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{environment}{thebibliography}
+% \changes{4.1b}{1993 Oct 18}{Add \cmd{\bibfont}, defaulted
+%                to \cmd{\relax}}
+% \changes{4.2}{1993 Oct 22}{Add coding for JGR, GRL, NLINPROC}
+% \changes{4.2}{1993 Nov 20}{Remove coding for AGU, since AGU-supplied
+%         coding is adequate but different}
+% \changes{5.1}{1994 Jun 22}{Put \cmd{\bibfont} at start so \cmd{\list}
+%     uses list parameters appropriate for the font size}
+% \changes{5.1}{1994 Jun 22}{Add \cmd{\if@openbib} as in \LaTeXe}
+% \changes{5.5}{1995 Mar 27}{Add special cross-ref citations for compatibility
+%     with \texttt{harvard}, \texttt{chicago}, and \texttt{named}}
+% \changes{6.1}{1995 Nov 22}{Replace \cs{if@openbib} with \cs{ifNAT@openbib}}
+% \changes{6.1}{1995 Dec 4}{Replace counter \texttt{enumiv} with
+%    \texttt{NAT@ctr} and refer to it explicitly, not with \cs{@listctr}}
+% \changes{6.1}{1995 Dec 4}{Use \cs{PackageWarning} for empty
+%      bibliography}
+%
+% The \texttt{thebibliography} environment is defined much as normal, except
+% that |\bibsetup| contains the special features for numerical or
+% author--year styles. The command |\bibfont| permits permits different
+% font sizes or styles to be used in the list. For example, for 
+% \textsl{Nonlinear Processes} it is |\small|. This means |\bibfont| must
+% be issued before the |\list| command, since the list parameters depend
+% on the current font size. For \textsl{AGU}, the whole
+% |\thebibliography| is left off, since the AGU-supplied coding will
+% do. It is only necessary to add |\noappendix| to the AGU coding.
+% 
+% I have replaced |\if@openbib| with |\ifNAT@openbib| in order to be
+% independent of the standard classes; this flag disappeared with the
+% December~1995 release of \LaTeX, so I do it myself just to be sure.
+% 
+% At the same time,
+% I have also decided to use my own counter |NAT@ctr| for the numericals;
+% previously I used |enumiv| as in the standard, and refered to it
+% elsewhere with |\@listctr|, but now I refer to it explicitly. This is to
+% avoid trouble if |\@listctr| should ever disappear. (The value of
+% |\@listctr| is set by |\usecounter|.)
+%    \begin{macrocode}
+\newcounter{NAT@ctr}
+%<*!agu>
+\renewenvironment{thebibliography}[1]{%
+ \bibfont\bibsection\parindent \z@\list
+   {\@biblabel{\arabic{NAT@ctr}}}{\@bibsetup{#1}%
+    \setcounter{NAT@ctr}{0}}%
+%<*!209&!subpack>
+    \ifNAT@openbib
+      \renewcommand\newblock{\par}
+    \else
+      \renewcommand\newblock{\hskip .11em \@plus.33em \@minus.07em}%
+    \fi
+%</!209&!subpack>
+%<209|subpack>      \def\newblock{\hskip .11em plus.33em minus.07em}%
+    \sloppy\clubpenalty4000\widowpenalty4000
+    \sfcode`\.=1000\relax
+%    \end{macrocode}
+% The files \texttt{chicago.bst} and \texttt{named.bst} can add the
+% commands |\citeN| and |\shortcite| respectively to the \texttt{.bbl}
+% files, for cross-referencing. Similarly, \texttt{harvard.bst} can add
+% |\citeasnoun|. These commands must therefore be accommodated, 
+% as least within the |thebibliography| environment.
+%    \begin{macrocode}
+%<newapa|chicago|all>    \let\citeN\cite \let\shortcite\cite
+%<harvard|all>    \let\citeasnoun\cite
+ }{\def\@noitemerr{%
+%<209>  \@warning
+%<!209>  \PackageWarning{natbib}
+     {Empty `thebibliography' environment}}%
+  \endlist\vskip-\lastskip}
+%<!egs>\let\bibfont=\relax
+%<egs>\let\bibfont=\small
+%</!agu>
+%<*agu>
+\let\aguthebib=\thebibliography
+\def\thebibliography#1{\noappendix\aguthebib{#1}}
+%</agu>
+%    \end{macrocode}
+% \end{environment}
+% 
+% \subsection{Compatibility Commands}
+% \begin{macro}{\reset@font}
+% \begin{macro}{\refname}
+% \changes{6.4}{1996 Jun 18}{Provide name with \LaTeXe\ too}
+% \begin{macro}{\bibname}
+% \changes{6.4}{1996 Jun 18}{Provide name with \LaTeXe\ too}
+% For older implementations of \LaTeX~2.09 (before December, 1991) the
+% |\reset@font| command does not exist. It is defined to be |\relax| under
+% normal \LaTeX{}, but does more under NFSS. In case it is not defined, add
+% it here. The naming commands |\bibname| and |\refname| are similarly
+% unknown for this old \LaTeX. They are sometimes even unknown in non-standard
+% classes that are used in place of \texttt{article}, \texttt{report}, and
+% \texttt{book}.
+%    \begin{macrocode}
+%<*!209>
+\providecommand\reset@font{\relax}
+\providecommand\bibname{Bibliography}
+\providecommand\refname{References}
+%</!209>
+%<*209>
+\@ifundefined{reset@font}{\let\reset@font=\relax}{}
+%<!agu&!egs>\@ifundefined{bibname}{\newcommand\bibname{Bibliography}}{}
+\@ifundefined{refname}{\newcommand\refname{References}}{}
+%</209>
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}
+%
+% \begin{macro}{\NAT@citeundefined}
+% \changes{6.1}{1995 Nov 22}{Add macro}
+% The December~1995 release of \LaTeX\ considered renaming the command
+% |\G@refundefinedtrue| for flagging undefined references. However, since a
+% number of packages, including \thestyle, were affected, it was decided to
+% retain the old name for the new coding. I had already decided to go for
+% an independent coding, which does exactly the same thing.
+%    \begin{macrocode}
+%<*!209>
+\newcommand\NAT@citeundefined{\gdef \NAT@undefined {%
+    \PackageWarningNoLine{natbib}{There were undefined citations}}}
+\let \NAT@undefined \relax
+%    \end{macrocode}
+% \end{macro}
+% \begin{macro}{\NAT@citemultiple}
+% \changes{6.1}{1995 Dec 6}{Add macro}
+% Add the warning about multiply-defined citations, as part of the
+% do-it-yourself |\bibcite| definition.
+%    \begin{macrocode}
+\newcommand\NAT@citemultiple{\gdef \NAT@multiple {%
+    \PackageWarningNoLine{natbib}{There were multiply defined citations}}}
+\let \NAT@multiple \relax
+\AtEndDocument{\NAT@undefined\NAT@multiple}
+%</!209>
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@mkboth}
+% \changes{6.1}{1995 Dec 4}{Provide macro in case it is removed from
+%     kernel}
+% Having been burned by the December~1995 update on several internal
+% commands, I have decided to make \thestyle\ as independent as
+% possible, or at least to avoid it crashing when internals are changed or
+% disappear in future. The |\@mkboth| is used in the bibliography listing,
+% and is the same as |\makeboth| with \texttt{headings} pagestyle. Provide
+% a dummy in case it disappears. If the kernel should use a different
+% command in future, the headings will not function, but at least there
+% will be no crash. (Also needed for very old versions of \LaTeX~2.09.)
+%    \begin{macrocode}
+%<209>\@ifundefined{@mkboth}{\newcommand\@markboth[2]{}}{}
+%<!209>\providecommand\@mkboth[2]{}
+%    \end{macrocode}
+% \end{macro}
+% 
+% \begin{macro}{\MakeUppercase}
+% \changes{6.1}{1995 Dec 4}{Provide compatibility for older versions}
+% The |\MakeUppercase| command replaces |\uppercase| in \LaTeXe\ of
+% June~1995. Provide it for earlier versions.
+%    \begin{macrocode}
+%<209>\let\MakeUppercase\uppercase
+%<!209>\providecommand\MakeUppercase{\uppercase}
+%    \end{macrocode}
+% \end{macro}
+%
+% \begin{macro}{\@extra@b@citeb}
+% \changes{6.4}{1996 Sep 1}{Add macro for \texttt{chapterbib.sty}}
+% \begin{macro}{\@extra@binfo}
+% \changes{6.4}{1996 Sep 1}{Add macro for \texttt{chapterbib.sty}}
+% Two commands used by the \texttt{chapterbib} package, but which must 
+% be defined to be nothing for use without that package. Do not |\let| them
+% be |\relax|, for that package checks if they exist (i.e., not |\relax|)
+% and redefines things like |\@citex|, which we do not want to have happen.
+% The necessary redefinitions are already included in \thestyle.
+%    \begin{macrocode}
+%<209>\@ifundefined{@extra@b@citeb}{\def\@extra@b@citeb{}}{}
+%<!209>\providecommand{\@extra@b@citeb}{}
+\gdef\@extra@binfo{}
+%    \end{macrocode}
+% \end{macro}\end{macro}
+%
+% \begin{macro}{\hyper@natanchorstart}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natanchorend}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natlinkstart}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% \begin{macro}{\hyper@natlinkend}
+% \changes{6.4}{1996 Oct 2}{Provide macro for \texttt{hyperref} package}
+% The \texttt{hyperref} package of Sebastian Rahtz and Yannis Haralambous 
+% defines these macros to
+% make hypertext links and references. Without that package, these macros
+% must be turned off. The order of loading \thestyle\ and \texttt{hyperref} 
+% should not be important.
+%    \begin{macrocode}
+%<*!209>
+\providecommand\hyper@natanchorstart[1]{}
+\providecommand\hyper@natanchorend{}
+\providecommand\hyper@natlinkstart[1]{}
+\providecommand\hyper@natlinkend{}
+%</!209>
+%<*209>
+\@ifundefined{hyper@natanchorstart}{\def\hyper@natanchorstart#1{}}{}
+\@ifundefined{hyper@natanchorend}{\def\hyper@natanchorend{}}{}
+\@ifundefined{hyper@natlinkstart}{\def\hyper@natlinkstart#1{}}{}
+\@ifundefined{hyper@natlinkend}{\def\hyper@natlinkend{}}{}
+%</209>
+%    \end{macrocode}
+% \end{macro}\end{macro}\end{macro}\end{macro}
+% 
+% \subsection{Sorting and Compression of Numbers}
+% The \texttt{cite} and (obsolete) \texttt{citesort} packages by Donald
+% Arseneau provide the coding for printing multiple citation numbers in
+% ascending order, and with a range where applicable. That is, if the
+% normal result of |\cite{..}| with several keys were [5, 3, 8, 4], the new
+% result would be [3--5, 8].
+% 
+% Since \texttt{cite.sty} totally reimplements the citation commands (as
+% does \thestyle) it is not possible to make the two compatible. Instead, I
+% have removed the necessary coding from \texttt{cite.sty}, converted it to
+% \thestyle\ format, and added it here. 
+% 
+% To activate the sorting and compression of numerical citations, load
+% \thestyle\ with the options \texttt{numbers,sort}.
+%  This coding has no effect on author--year citations.
+%
+% \begin{macro}{\NAT@citen}
+% \changes{6.4}{1996 Oct 11}{Add coding from \texttt{cite.sty}}
+% It is not included in the \LaTeX~2.09 version, nor in the journal packages
+% since it is turned on by a package option, something missing in both of
+% them. Besides, the journals are author--year mode.
+%    \begin{macrocode}
+%<*!subpack&!209>
+\ifnum\NAT@sort=1
+\newcommand\NAT@citen[1]{%
+\nocite{#1}%
+\@tempcntb\m@ne
+\let\@h@ld\relax
+\let\@citea\@empty
+\let\@celt\delimiter 
+\def\@cite@list{}% 
+\@for \@citeb:=#1\do{\@make@cite@list}%
+\@tempcnta\m@ne
+\let\@celt\@compress@cite \@cite@list 
+\@h@ld}
+
+\begingroup \catcode`\_=8 
+\gdef\@make@cite@list{%
+     \edef\@citeb{\expandafter\@firstofone\@citeb}%
+     \@ifundefined{b@\@citeb\@extra@b@citeb}{%
+      \@citea{\reset@font\bfseries?}\def\@citea{\NAT@sep\penalty\@m\NAT@space}%
+      \NAT@citeundefined\PackageWarning{natcite}%
+      {Citation `\@citeb' on page \thepage\space undefined}}%
+    {\NAT@parse{\@citeb}%
+      \ifcat _\ifnum\z@<0\NAT@num _\else A\fi % a positive number, put in list
+       \@tempcnta\NAT@num \relax
+       \ifnum \@tempcnta>\@tempcntb % new highest, add to end (efficiently)
+          \edef\@cite@list{\@cite@list \@celt{\NAT@num}}%
+          \@tempcntb\@tempcnta
+       \else % arbitrary number: insert appropriately
+          \edef\@cite@list{\expandafter\@sort@celt \@cite@list \@gobble @}%
+       \fi
+    \else % citation is not a number, output immediately
+       \@citea \NAT@num \def\@citea{\NAT@sep\penalty\@m\NAT@space}%
+ \fi}}
+\endgroup
+
+\def\@compress@cite#1{%
+  \advance\@tempcnta\@ne
+  \ifnum #1=\@tempcnta  
+     \ifx\@h@ld\relax   
+        \edef\@h@ld{\@citea #1}%
+     \else              
+        \def\@h@ld{\hbox{--}\penalty\@m #1}%
+     \fi 
+  \else  
+     \@h@ld \@citea #1\let\@h@ld\relax
+  \fi \@tempcnta#1\def\@citea{\NAT@sep\penalty\@m\NAT@space}%
+}
+
+\def\@sort@celt#1#2{\ifx \@celt #1%
+     \ifnum #2<\@tempcnta 
+        \@celt{#2}%
+        \expandafter\expandafter\expandafter\@sort@celt 
+     \else
+        \@celt{\number\@tempcnta}\@celt{#2}% 
+  \fi\fi}
+\def\NAT@citexnum[#1][#2]#3{\let\@citea\@empty
+  \@cite{\NAT@citen{#3}}{#1}{#2}}
+\fi
+%</!subpack&!209>
+%    \end{macrocode}
+% \end{macro}
+%
+% \subsection{Local Configuration}
+% \changes{5.2}{1994 Aug 25}{Add reading in of \texttt{natbib.cfg}}
+% \changes{5.5}{1995 Mar 21}{Local configuration read in at end}
+% To accommodate local additional |\bibstyle@| definitions, 
+% or any other modifications to the coding, read in
+% configuration file \texttt{natbib.cfg} if it exists. 
+%    \begin{macrocode}
+%<*!subpack&!209>
+\InputIfFileExists{natbib.cfg}
+       {\typeout{Local config file natbib.cfg used}}{}
+%</!subpack&!209>
+%</package>
+%    \end{macrocode}
+% 
+% \Finale
-- 
cgit v1.2.3

