@book{8087,
	author = {Gregg, Michael B.},
	title = {Field epidemiology /},
	publisher = {Oxford University Press,},
	year = {2002.},
	address = {Oxford ;},
	edition = {2nd ed.},
	url = {http://www.loc.gov/catdir/toc/fy031/2001133067.html}
}