@book{563202,
	author = {Cochran, William G.},
	title = {Sampling techniques, 3rd edition /},
	publisher = {Wiley,},
	year = {1977},
	address = {[S.l.] :},
	url = {http://www.amazon.com/exec/obidos/ASIN/047116240X/chopaconline-20}
}