@book{770315,
	author = {Davis Bruce Ellsworth. and Bruce E. Davis},
	title = { GIS : a visual approach},
	publisher = {Delmar Thomson Learning,},
	year = {2001},
	address = {Albany, N.Y.,},
	edition = {2nd Edition},
	note = {In this update of the 1996 introduction to the geographic information system, Davis (geography and planning, Eastern Kentucky U.) continues his use of a visual set approach with key concept illustrations and corresponding text to this computer technology and methodology for collecting}
}