%&LaTeX
\documentclass{article}

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

\begin{document}

\begin{thebibliography}{1}

\bibitem{Leibundgut_etal2009} Leibundgut, C., Maloszewski, P., \& K{\"u}lls, C. (2009). \textit{Tracers in Hydrology}. John Wiley \& Sons, Ltd.

\end{thebibliography}

\end{document}

