%&LaTeX
\documentclass{article}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{textcomp}

\begin{document}

\begin{thebibliography}{1}

\bibitem{Gantenbein_etal2009} Gantenbein, B., Pitscheider, G., Gammeter, H., Leherr, H., M{\"a}der, R., Rink, S., et al. (2009). \textit{Handbuch FOSUMOS}. Wattwil: Forum Suchtmedizin Ostschweiz (FOSUMOS).

\end{thebibliography}

\end{document}

