1. Cognitive Ethology;Allen;Animal Behaviour,1997
2. Self-recognition in non-human primates: past and future challenges;Anderson,1999
3. Assessment of pain in animals;Bateson;Animal Behaviour,1991
4. An Introduction to the Principles of Morals and Legislation;Bentham,1789
5. The Animal Issue: Moral Theory in Practice;Carruthers,1992