@book{132133,
	author = {Otto, Ken and Purvin & Gertz and Otto, Ken},
	title = {World LPG Trade Patterns Poised for Rapid Change},
	publisher = {Purvin & Gertz},
	year = {1999},
	address = {Houston, Texas},
	note = {Sitio visitado en julio de 2001 ; Navegadores de Internet},
	url = {http://www.purvingertz.com/ogj061499.html}
}