@book{7056,
	author = {Maxwell, John C., and Valverde, Hubert },
	title = {Las 21 leyes irrefutables del liderazgo :},
	publisher = {Grupo Nelson,},
	year = {c2007.},
	address = {Nashville :},
	url = {http://www.loc.gov/catdir/enhancements/fy1010/2010285725-d.html}
}