https://www.spreaker.com/episode/prof-jose-a-r-l-gonzalez-singer-peter-2002-animal-liberation-new-york-ecco-324-p-isbn-0060011572--44952383
Prof. José A.R.L. González: SINGER, Peter (2002) – Animal liberation. New York : Ecco. 324 p. ISBN 0060011572.