%&LaTeX
\documentclass{article}

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

\begin{document}

\begin{thebibliography}{1}

\bibitem{Giare_etal2021} Giare, W., Di Valentino, E., Melchiorri, A., \& Mena, O. (2021). New cosmological bounds on hot relics: axions and neutrinos. \textit{Mon. Not. Roy. Astron. Soc.}, \textit{505}(2), 2703--2711.

\end{thebibliography}

\end{document}

