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