@book{40048,
	author = {Villoro Toranzo, Miguel. and Editorial Porrúa.},
	title = {Introducción al estudio del derecho},
	publisher = {Editorial Porrúa},
	year = {1980.},
	series = {Colección Porrúa},
	address = {México},
	edition = {4a ed.}
}