@book{33,
	author = {Mendenhall, William. and Beaver, Robert J.},
	title = {Introduction to probability and statistics /},
	publisher = {Thomson-Brooks/Cole,},
	year = {2009},
	address = {Pacific Grove, CA :},
	edition = {Thirteenth edition /},
	url = {http://www.loc.gov/catdir/enhancements/fy1514/2002104701-d.html}
}