@book{210758,
	author = {Webb, Penny, and Bain, Chris,},
	title = {Essential epidemiology :},
	publisher = {Cambridge University Press,},
	year = {2005.},
	address = {New York, NY :},
	url = {http://www.loc.gov/catdir/enhancements/fy0632/2004057005-d.html}
}