\bibitem
........

   \bibitem[label]{cite_key}

   The \bibitem command generates an entry labelled by label.  If the
the enumi counter.  The cite_key is any sequence of letters, numbers,
and punctuation symbols not containing a comma.  This command writes an
entry on the .aux file containing cite_key and the item's label.  When
this .aux file is read by the \begin{document} command, the item's