@book{80977,
	author = {Beltrán, Virgilio and I. Braun, Eliezer, coautÌÌ},
	title = {Principios de físia : curso de introducciòn / Beltrán Virgilio, Eliezer Braun, coaut},
	address = {México : Trillas, 1990},
	edition = {2}
}