@Book{BVMC:669637,
author = {Bárcena, Mariano},
title = {Los ópalos de México: memoria presentada a la Sociedad Mexicana de Historia Natural},
publisher = {Alicante : Biblioteca Virtual Miguel de Cervantes, 2014},
year = {2014},
url = {http://www.cervantesvirtual.com/nd/ark:/59851/bmch14v9}
}