@book{4662,
	author = {Tirado, Carlos and Calleja Medel, Gilda},
	title = {Como dominar la aritmética comercial en 90 días :},
	publisher = {Círculo de Lectores,},
	year = {1980.},
	series = {Autoaprendizaje},
	address = {Bogotá :},
	edition = {1a. ed.}
}