@book{239,
	author = {Sommer, Barbara Baker, and Sommer, Robert.},
	title = {A practical guide to behavioral research :},
	publisher = {Oxford University Press,},
	year = {1997.},
	address = {New York :},
	edition = {4th ed.},
	url = {http://www.loc.gov/catdir/enhancements/fy0605/96035531-d.html}
}