@book{133675,
	author = {Gordis, Leon},
	title = {Epidemiology /},
	publisher = {Elsevier/Saunders,},
	year = {c2009.},
	address = {Philadelphia :},
	edition = {4th ed.},
	url = {http://www.loc.gov/catdir/toc/ecip0723/2007030111.html}
}