\begin{thebibliography}{widest-label} \bibitem[label]{cite_key} . . . \end{thebibliography}
The thebibliography
environment produces a bibliography or
reference list. In the article
style, this reference list is
labelled "References"; in the report
style, it is labelled
"Bibliography".
widest-label
: Text that, when printed, is approximately as wide
as the widest item label produces by the \bibitem
commands.