@book{111996,
	author = {Ryan, Julie and Williams, Julian and ebrary, Inc.},
	title = {Children's mathematics 4-15},
	publisher = {McGraw-Hill/Open University Press,},
	year = {2007.},
	address = {Maidenhead :},
	url = {http://site.ebrary.com/lib/strathmore/Doc?id=10197012}
}