natbib.cfg

% natbib.cfg
\AtBeginDocument{%
\@ifpackageloaded{authorindex}{%
\ifNAT@numbers
\let\org@@citex\NAT@citexnum
\else
\let\org@@citex\NAT@citex
\fi
\def\@citex[#1][#2]#3{%
\typeout{indexing: [#1][#2]{#3}}%
\org@@citex[#1][#2]{#3}%
\@aicitey{#3}}%
\renewcommand\NAT@wrout[5]{%
\if@filesw{%
\let\protect\noexpand\let~\relax
\immediate\write\@auxout{\string\aibibcite{#5}{#1}}%
\immediate\write\@auxout{\string\bibcite{#5}{{#1}{#2}{{#3}}{{#4}}}}}%
\fi}}{}}
\endinput