%&LaTeX
\documentclass{article}

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

\begin{document}

\begin{thebibliography}{1}

\bibitem{vanWalsem2019} van Walsem J (2019) Design and optimization of a photocatalytic reactor for air purification in ventilation systems. 158 p

\end{thebibliography}

\end{document}

