\ProvidesPackage{natbib}
\input{natbib-common.hva}
\renewcommand{\@biblabel}[1]
{\NAT@bibread{#1}\purple\NAT@format@item{#1}{\NAT@num}{\NAT@auth}{\NAT@year}}
\renewcommand{\@bibref}[3]
{{\def\@tmp{#2}\ifx\@tmp\@empty{}???\else\NAT@format@cite{#2}{#3}{#1}\fi}}
