@book{135778,
	author = {Mertens, Donna M. and Wilson, Amy T. and ebrary, Inc.},
	title = {Program evaluation theory and practice},
	publisher = {Guilford Press,},
	year = {c2012.},
	address = {New York, N.Y. :},
	url = {http://site.ebrary.com/lib/rucke/Doc?id=10539287}
}