@book{1957,
	author = {Berry, William Dale.},
	title = {Nonrecursive causal models /},
	publisher = {Sage Publications,},
	year = {c1984.},
	address = {Beverly Hills, Calif. :},
	url = {http://www.loc.gov/catdir/enhancements/fy0654/83051542-d.html}
}