@book{35459,
	author = {Fletcher, Robert H.  and Fletcher, Suzanne W.},
	title = {Clinical epidemiology :},
	publisher = {Lippincott Williams & Wilkins,},
	year = {2005.},
	address = {Philadelphia :},
	edition = {4th ed.},
	url = {http://www.loc.gov/catdir/toc/ecip0510/2005008293.html}
}