@book{15349,
	author = {Spencer, Peter Lincoln and Brydegaard, Marguerite},
	title = {Building mathematical competence in the elementary school},
	publisher = {Holt, Rinehart and Winston},
	year = {1952.},
	address = {New York},
	note = {Published in 1952 under title: Building mathematical concepts in the elementary school.}
}