@book{6184,
	author = {Engel, Arthur. and ebrary, Inc.},
	title = {Problem-solving strategies},
	publisher = {Springer,},
	year = {c1998.},
	series = {Problem books in mathematics},
	address = {New York :},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=5006011}
}