por Singer, Peter, 1946- [autor] | Soler Chic, Joan [traductor] | Singer, Peter. Ethics in the real world.
por Singer, Peter, 1946- [autor] | Herrera Bonet, Rafael [traductor] | Singer, Peter, 1946-. Practical ethics.
por Singer, Peter [editor] | Vigil Rubio, Jorge [traductor] | Vigil, Margarita [traductor].