@book{21561,
	author = {Koon, Cline Morgan,},
	title = {Sources of visual aids and equipment for instructional use in schools,},
	publisher = {U.S. Govt. Print. Off.,},
	year = {1937.},
	series = {U.S. Office of Education. Pamphlet},
	address = {Washington,},
	note = {Later edition by U.S. Office of Education.}
}