@book{8714,
	author = {Campbell, Donald Thomas,},
	title = {Diseños experimentales y cuasiexperimentales en la investigación social},
	publisher = {Amorrortu},
	year = {1973},
	series = {Biblioteca de sociologia},
	address = {Buenos Aires},
	note = {Translation of : Experimental and quasi-experimental designs for research.}
}