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Kheel, Marti. 2004. The History of Vegetarianism. In Shepard Krech III, C. Merchant, and J.R. McNeil (eds.), The Encyclopedia of World Environmental History, Vol 3, 1273-1278. New York: Routledge.

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Barton, M. 1987. Animal Rights. London: Watts .

Thompson, Paul B. and A. Nardone. 1999. Sustainable livestock production: Methodological and ethical challenges. Livestock Production Science 61: 111-119.

Broom, Donald. 2014. Sentience and Animal Welfare. CABI.

Thompson, Paul B., Michael Appleby, Lawrence Busch, Linda Kalof, Mara Miele, Bailey F. Norwood, Edward Pajor. 2011. Values and Public Acceptability Dimensions of Sustainable Egg Production. Poultry Science 90, 2097-2109.

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Levin, M.E. 1977. Animal rights evaluated. The Humanist 37: 12-15.

Bateson, P.P.G. and Peter H. Klopfer (eds.). 1991. Perspectives in Ethology (vol. 9): Human Understanding and Animal Awareness. New York: Plenum.

Palmer, Julian. 2001. Animal Law. 3rd ed. Crayford, England: Shaw.

Varner, Gary E. 2012. Personhood, Ethics, and Animal Cognition: Situating Animals in Hare's Two Level Utilitarianism. New York: Oxford University Press.

Scruton, Roger. 1996. Animal Rights and Wrongs. London: Demos.

Bekoff, Marc. 2007. The Emotional Lives of Animals: A Leading Scientist Explores Animal Joy, Sorrow, and Empathy - and Why They Matter. New World Library.

Singer, Peter. 1987. Liberation of animal rights. Monist 70(1): 3-14.

Bekoff, Marc and John A. Byers. 1998. Animal Play : Evolutionary, Comparative, and Ecological Perspectives. New York: Cambridge University Press.

Dupré, John. 2006. Humans and Other Animals. Oxford: Clarendon Press.

Youatt, William, 1776-1847; Preece, Rod. 2003, 1839. The Obligation and Extent of Humanity to Brutes: Principally Considered with Reference to Domesticated Animals (1839). Lewiston, NY: Edwin Mellen Press.

Garner, Robert. 2005. Animal Ethics. Cambridge: Polity Press.

Zwart, Hub. 1997. What is an animal? A philosophical reflection on the possibility of a moral relationship with animals. Environmental Values 6(4): 377-392.

Ingold, Tim (ed.). 1994. What is an Animal? London: Routledge.

Bahlig-Pieren, Z. and D.C. Turner. 1999. Anthropomorphic interpretations and ethological descriptions of dog and cat behavior by lay people. Anthrozoös 12(4): 205-210.