@book{49199,
	author = {Verstappen, H.Th.},
	title = {An atlas illustrating the use of aerial photographs in geomorphological mapping},
	publisher = {International Institute for Aerial Survey and Earth Sciences,},
	year = {1977},
	series = {ITC Textbook of photo-interpretation vol. 7 chapter 5},
	address = {Enschede, The Netherlands :}
}