@book{7711,
	author = {Shadish, William R. and Campbell, Donald T., },
	title = {Experimental and quasi-experimental designs for generalized causal inference /},
	publisher = {Wadsworth CENGAGE Learning, },
	year = {c2002},
	address = {Boston, MA :},
	url = {https://www.cicy.mx/sitios/sib/doctoelectronico/8419.pdf}
}