%&LaTeX
\documentclass{article}

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

\begin{document}

\begin{thebibliography}{10}

\bibitem{Aggarwal+Figueroa2021} Aggarwal, N. et al, \& Figueroa, D. G. (2021). Challenges and opportunities of gravitational-wave searches at MHz to GHz frequencies. \textit{Living Rev. Relativ.}, \textit{24}(1), 4--74pp.

\end{thebibliography}

\end{document}

