@techreport{Becker2018,
author = {Becker, R.A. and Wilks, A.R. and Brownrigg, R. and Minka, T.P. and Deckmyn, A.},
title= {maps: Draw Geographical Maps},
year = {2018},
URL = {https://CRAN.R-project.org/package=maps},
institution = {R package version 3.3.0},
}