@book{33269,
	author = {Lagakos, Stephen W. and Institute of Medicine (U.S.).},
	title = {Methodological challenges in biomedical HIV prevention trials /},
	publisher = {National Academies Press,},
	year = {c2008.},
	address = {Washington, D.C. :},
	url = {http://search.nap.edu/nap-cgi/de2007.cgi?term=0309114306}
}