To cite the \emph{ mprobit } Zelig model:
 \begin{verse}
 Kosuke Imai. 2009. "mprobit: Multinomial Probit Model via Markov Chain Monte Carlo Method" in Kosuke Imai, Gary King, and Olivia Lau, "Zelig: Everyone's Statistical Software,"\url{http://gking.harvard.edu/zelig} 
\end{verse}