@book{33569,
	author = {Bryk, Anthony S. and Raudenbush, Stephen W.},
	title = {Hierarchical linear models :},
	publisher = {Sage Publications,},
	year = {c1992.},
	address = {Newbury Park :},
	url = {http://www.loc.gov/catdir/enhancements/fy0655/91045334-d.html}
}