\documentclass{article}

\usepackage{amsmath}
\usepackage{caption}
\usepackage{amsthm}
\newtheorem{lemma}{Lemma}

\begin{document}

\section{Foo}%
\label{sec:foo}

\begin{equation}%
\label{eq:foo}
    1 + 1 = 2
\end{equation}

\begin{equation}%
\label{eq:bar}
    1 + 1 = 2
\end{equation}

\begin{figure}%
\LaTeX{}
\caption{Baz}%
\label{fig:baz}
\end{figure}

\begin{lemma}%
\label{thm:foo}
    1 + 1 = 2
\end{lemma}

\include{bar}

\end{document}
