@book{51740,
	author = {Keegan, Desmond. and Educational Resources Information Center (U.S.)},
	title = {On the nature of distance education /},
	publisher = {ERIC,},
	year = {1980.},
	series = {ZIFF Papiere ;},
	address = {Washington, D.C. :},
	note = {"ED 311 890."}
}