@book{3039,
	author = {National Geographic Society},
	title = {Field guide to the birds of North America},
	publisher = {National Geographic; },
	year = {1987},
	address = {Washington, D.C. : },
	edition = {Cuarta edición revisada y adaptada},
	note = {Incluye índice.},
	url = {http://www.loc.gov/catdir/description/simon034/2003269768.html}
}