%&LaTeX
\documentclass{article}

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

\begin{document}

\begin{thebibliography}{1}

\bibitem{Keiz1965} Keiz, G. (1965). \textit{Fischereibiologische Untersuchungen {\"u}ber den Prebersee (Land Salzburg)} (Vol. 7).

\end{thebibliography}

\end{document}

