@book{68241,
	author = {Selltiz, Claire and Wrightsman, Lawrence S.},
	title = {Métodos de investigación en las relaciones  sociales },
	publisher = {: Ediciones Rialp},
	year = {, 1980},
	address = {Madrid},
	edition = {9a. edición},
	note = {Título original: Research methods in social relations}
}