%&LaTeX
\documentclass{article}

\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{textcomp}

\begin{document}

\begin{thebibliography}{10}

\bibitem{Jaeckel1952} Jaeckel, S. (1952). \textit{Unsere S{\"u}{\ss}wassermuscheln}. Die Neue Brehm-B{\"u}cherei. Westarp-Verlag.

\end{thebibliography}

\end{document}

