@book{9561,
	author = {Erickson, Jon. and Español Echaniz, Ignacio.},
	title = {La Extinción de las especies },
	publisher = {McGraw-Hill, },
	year = {D.L. 1992.},
	series = {Serie McGraw-Hill de divulgación científica},
	address = {Madrid [etc.] : }
}