@misc{Willekens2012,
author = {Willekens, F.},
title= {Biograph: Explore life histories. R package},
year = {2012},
URL = {http://cran.r-project.org/web/packages/Biograph/index.html },
note = {(Accessed January 16, 2013)},
edition = {2.0.2},
}