\documentclass{report}
\usepackage{amssymb, amsmath, hyperref}
\usepackage{preamble}

\begin{document}

\input{./src/cat/index}
\input{./src/topology/index}
\input{./src/fa/index}
\input{./src/measure/index}
\input{./src/dg/index}
%\input{./src/process/index}

\bibliographystyle{alpha} % We choose the "plain" reference style
\bibliography{refs.bib} % Entries are in the refs.bib file


\end{document}
