@book{5323,
	author = {Campbell, Stephen R. and ebrary, Inc.},
	title = {Learning and teaching number theory},
	publisher = {Ablex Pub.,},
	year = {2002.},
	series = {Mathematics, learning, and cognition. monograph series of the Journal of mathematical behavior ;},
	address = {Westport, Conn. :},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10002019}
}