\input showtags.sty

\ifx\nullocplist\undefined
\def\@bibitem#1{\item\if@filesw {\let\protect\noexpand\immediate\write\@auxout
    {\string\bibcite{#1}{\the\value{\@listctr}\string\make@josa{\the\value{\@listctr}}}}\fi\ignorespaces}
  \@showtag{#1}}
%
\def\@lbibitem[#1]#2{\item[\@biblabel{#1}\hfill]\if@filesw
  {\let\protect\noexpand
    \immediate
    \write\@auxout{\string\bibcite{#2}{#1\string\make@josa{#1}}}}\fi\ignorespaces
  \@showtag{#2}}
\fi
\endinput