\chapter{Reference management}
\label{sec:literature}

For typesetting our first theses in \LaTeX{}, the last core functionality to learn is citing literature.
Our references are gathered in a bibliography file.
Once we reference one of its entries from our \LaTeX{} document, Bib\TeX{} (a program similar to the standard \acro{PDF}\LaTeX{} compiler) can insert automatically generated citations.
It will format them in a bibliography style of our choice.

\section{The bibliography file}
Our \textbf{bibliography collection} consists of multiple literature entries in a pre-defined format, such that they can be processed by Bib\TeX{}.
An exemplary item can be seen in \cref{lst:bibfile-sample-entry}.

\begin{figure}[H]
  \begin{minted}[autogobble]{latex}
  @article{turing1990,
    title={The chemical basis of morphogenesis},
    author={Turing, Alan Mathison},
    journal={Bulletin of mathematical biology},
    volume={52},
    pages={153--197},
    year={1990},
    publisher={Springer}
  }
  \end{minted}
  \caption{Exemplary bibliography entry}
  \label{lst:bibfile-sample-entry}
\end{figure}

The type of the bibliography entry is specified after the opening \texttt{@} sign (e.\,g., article, book, proceedings, …).
What follows is a list of important attributes like title and author.
Whether they are required or not depends on the entry type.
In any case, we will need the first entry after the opening braces: the Bib\TeX{} key.
This is the identifier that we will use to reference the entry in our \LaTeX{} document.
Bib\TeX{} keys can be chosen freely, but have to be unique.
Typically, they will consist of a combination of authors, publication dates, and topics.

\textbf{Bibliography files} can be compiled manually, yet it is more common to use programs like JabRef,\footnote{Cf. \url{https://www.jabref.org/}.} Zotero\footnote{Cf. \url{https://www.zotero.org/}.} or the widely-used software Citavi\footnote{Vgl. \url{https://www.citavi.com/de}.}.
While JabRef operates directly on your bibliography file, Zotero and Citavi projects\footnote{Vgl. \url{https://www1.citavi.com/sub/manual5/de/exporting_to_bibtex.html}.} can be exported to bibliography files to use them in \LaTeX{} documents.

\textbf{Bibliography entries} are provided by many academic search engines, including Google Scholar (cf. \cref{fig:google-scholar-bibtex}).
When using them, make sure that the entries are cohesive across your reference collection and complete with regard to their attributes.
A high-quality (although, unfortunately, incomplete) source for Bib\TeX{} entries is the dblp Computer Science Library\footnote{Available at \url{https://dblp.org/search}.}.

\begin{figure}[H]
  \includegraphics[width=\textwidth]{graphics/google_bibtex1.jpg}  
  \includegraphics[width=\textwidth]{graphics/google_bibtex2.jpg}  
  \caption{Loading Bib\TeX{} entries from Google Scholar}
  \label{fig:google-scholar-bibtex}
\end{figure}

\section{Citing}
Bib\TeX{} extends \LaTeX{} by several commands (cf. \cref{tbl:bibtex-commands}). 
Make sure to include the \mintinline{sh}{natbib} package for this purpose.

\begin{table}[H]
  \centering
  \begin{tabular}{ll}
  \toprule
  Function                 & Command \\ \midrule
  Citing sources           & \mintinline{latex}{\cite{<source>}} \\
  Citing pages             & \mintinline{latex}{\cite[p. 15]{<source>}} \\
  Custom citations         & \mintinline{latex}{\cite[<prefix>][<suffix>]{<source>}} \\
  Including the bibliography     & \mintinline{latex}{\bibliography{<bibliographyfile>}} \\
  Setting the bibliography style & \mintinline{latex}{\bibliographystyle{<style>}} \\ \bottomrule
  \end{tabular}
  \caption{Commands for citations}
  \label{tbl:bibtex-commands}
\end{table}

The \mintinline{latex}{<source>} of a citation is always a Bib\TeX key.
The list of available citation styles\footnote{Head to Overleaf for a rather complete list: \url{https://www.overleaf.com/learn/latex/Biblatex_citation_styles}} includes alpha, natdin, and apa.
The table of references will always appear where the \mintinline{latex}{\bibliography{…}} command was put.
The \mintinline{latex}{\cite} command comes with many variants.\footnote{Cf. \url{https://www.economics.utoronto.ca/osborne/latex/BIBTEX.HTM.}}

\Example{lst:natdin-example}{literature/natdin-example}{literature/natdin-example_bib}{Examplery citations in the \mintinline{latex}{natdin} style.}
