@techreport{Keitt2009,
author = {Keitt, T.H. and Bivand, R.S. and Pebesma, E.J. and Rowlingson, B.},
title= {rgdal: Bindings for the Geospatial Data Abstraction Library},
year = {2009},
URL = {http://CRAN.R-project.org/package=rgdal},
}