@book{4,
	author = {Foreman, E. K.,},
	title = {Survey sampling principles /},
	publisher = {Dekker,},
	year = {c1991.},
	series = {Statistics, textbooks and monographs ;},
	address = {New York :},
	url = {http://www.loc.gov/catdir/enhancements/fy0745/91016179-d.html}
}