\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

%These two are needed because biblatex provides \nolinkurl and \url
\usepackage{url}
\providecommand*{\nolinkurl}{\url}

\usepackage{amssymb} % Just for \mathbb
\usepackage{cite}
%% \usepackage[style=numeric, backend=biber]{biblatex}
%% \usepackage{biblatex2bibitem}
%%
%% \addbibresource{biblatex-examples.bib}
%%
%% \addbibresource{biblatex2bibitem-examples.bib}

\begin{document}
\cite{sigfridsson,knuth:ct:e}.

See also \cite{solymosi2010question,halbeisen2019geometric,Kohnert2006IntegralPS}.

\begin{thebibliography}{99}
{}
\bibitem{halbeisen2019geometric}
Lorenz Halbeisen and Norbert Hungerbühler. ‘A geometric
representation of integral solutions of $x^2+ xy+ y^2= m^2$’. In:
\emph{Quaestiones Mathematicae} (2019), pp. 1–15.
{}
\bibitem{knuth:ct:e}
Donald E. Knuth. \emph{Computers \& Typesetting}. Vol. E:
\emph{{Computer Modern} Typefaces}. Reading, Mass.:
Addison-Wesley, 1986.
{}
\bibitem{Kohnert2006IntegralPS}
Axel Kohnert and Sascha Kurz. ‘Integral point sets over {$\mathbb
{Z}^m_n$}’. In: \emph{Discrete Applied Mathematics} 157 (2006),
pp. 2105–2117.
{}
\bibitem{sigfridsson}

Emma Sigfridsson and Ulf Ryde. ‘Comparison of methods for deriving
atomic charges from the electrostatic potential and moments’. In:
\emph{Journal of Computational Chemistry} 19.4 (1998), pp. 377–395.
\textsc{doi}: \nolinkurl
{10.1002/(SICI)1096-987X(199803)19:4<377::AID-JCC1>3.0.CO;2-P}.
{}
\bibitem{solymosi2010question}
Jozsef Solymosi and Frank De Zeeuw. ‘On a question\relax ~of Erdős
and Ulam’. In: \emph{Discrete \& Computational Geometry} 43.2
(2010), pp. 393–401. arXiv: \nolinkurl {0806.3095_}. \textsc{url}: \url
{https://example.com/@%D1%80%D1%83%D1%81_}.
\end{thebibliography}

%% \printbibliography
%%
%% \printbibitembibliography
\end{document}