@book{44951,
	author = {Gregory, Ian N. and Ell, Paul S.},
	title = {Historical GIS :},
	publisher = {Cambridge University Press,},
	year = {2007.},
	series = {Cambridge studies in historical geography ;},
	address = {Cambridge ;},
	url = {http://www.loc.gov/catdir/enhancements/fy0729/2007032991-b.html}
}