@book{154172,
	author = {Wagner, Richard and Vélez Guevara, Carlos Vicente},
	title = {Guía de La valquiria de Richard Wagner},
	publisher = {CVG},
	year = {1991.},
	address = {San Juan, P.R.},
	edition = {1a ed.},
	note = {Libretto by the composer.}
}