@book{256179,
	author = {Sheffield, Linda Jensen, and Texas Association for the Gifted and Talented.},
	title = {Extending the challenge in mathematics :},
	publisher = {Corwin Press,},
	year = {c2003.},
	address = {Thousand Oaks, CA :},
	url = {http://www.loc.gov/catdir/enhancements/fy0658/2002013710-d.html}
}