@misc{Ševčíková2013,
author = {Ševčíková, H. and Gerland, P. and Andreev, K. and Li, N. and Gu, D. and Spoorenberg, T. },
title= {wpp2012: World Population Prospects 2012. R package version 2.2-1},
year = {2013},
URL = {http://cran.r-project.org/package=wpp2012 },
}