@book{7717,
	author = {Cochran, William G.},
	title = {Sampling Techniques, 3rd edition /},
	publisher = {John Wiley & Sons,},
	year = {1977.},
	address = {[S.l.] :},
	edition = {3rd ed.},
	url = {http://www.amazon.com/exec/obidos/ASIN/047116240X/chopaconline-20}
}