@book{68809,
	author = {Marks, John L. and Purdy, Charles Richard},
	title = {Teaching arithmetic for understanding},
	publisher = {McGraw-Hill},
	year = {c [1958]},
	series = {McGraw-Hill series in education. Supervision, curriculum, and methods in education},
	address = {New York},
	note = {First ed. published in 1958 under title: Teaching arithmetic for understanding.}
}