@book{23271,
	author = {Butzer, Karl W. and Omo Research Expedition},
	title = {Recent history of an Ethiopian delta :},
	publisher = {University of Chicago, Dept. of Geography,},
	year = {c1971.},
	series = {University of Chicago geography research paper ;},
	address = {Chicago :},
	note = {"Contribution no. 25 of the Omo Research Expedition (University of Chicago Group)".}
}