Referencias

\section{Introduction} \label{introduction}
This is an introductory paragraph with some dummy text. This section 
will be later referenced.
 
\begin{figure}[h]
\centering
\includegraphics[width=0.3\linewidth]{lion-logo.png}
\caption{This image will be referenced below}
\label{fig:lion}
\end{figure}
 
You can reference images, for instance, the image \ref{fig:lion} shows 
the red lion logo.
 
\section{Math references} \label{mathrefs}
As mentioned in section \ref{introduction}, different elements can be 
referenced within a document