Allport, GW. 1954. The nature of prejudice. Cambridge, Mass: Addison-Wesley.

Butterworth, J & Thwaites, G. 2005. Thinking skills, Cambridge: Cambridge University.

Bentham, J. 1970. Introduction to the principles of morals and legislation. London: Athlone.

Barnett, HA. 1997. Sourcebook on feminist jurisprudence. London: Cavendish.

Collins, BE. 1970. Social psychology. Emeryville: Calif: Addison-Wesley.

Cozic, CP & Petriken, J. 1995. The abortion controversy. San Diego, Calif: Greenhaven.

Descartes, R. 1986. Meditations on first philosophy. Cambridge: Cambridge University.

Friedman, M. 2002. Social responsibility of business is to increase its profits, pp. 225–230, in Perspectives in business ethics, edited by LP Hartman. Boston: McGraw-Hill.

Honderich, T (ed). 1995. The Oxford companion to philosophy. Oxford: Oxford University.

Kahane, H & Cavender, N. 2006. Logic and contemporary rhetoric. Belmont, Mass: Wadsworth/Thomson Learning.

LeGuin, U. 1992. The lefthand of darkness. London: Orbit.

Merleau-Ponty, M. 1964. Signs. Evanston, Ill: Northwestern University.

Milgram, S. 1974. Obedience to authority: an experimental view. London: Tavistock.

Olen, J & Barry, V. 1999. Applying ethics: a text with readings. Belmont, Calif: Wadsworth.

Plato. 1966. The Republic. London: Longmans.

Sparks, AW. 1991. Talking philosophy: a wordbook. London: Routledge.

The Guardian, Wednesday 17 November 2004.

Teays, W. 2003. Second thoughts: critical thinking for a diverse society. Boston: McGraw-Hill.

Van den Berg, MES. 2010. Critical reasoning and the art of argumentation. Pretoria: Unisa Press.

Van den Haag, E. 1998. On deterrence and the death penalty, pp. 47–58, in Capital punishment: a reader. Edited by Glen H. Stassen. Cleveland, Ohio: Pilgrim.

Wasserstrom, RA. 1997. A defence of programs of preferential treatment, pp. 198–204, in Affirmative action: social justice or reverse discrimination? Edited by FJ Beckwith & TE Jones. Amherst, New York: Prometheus.

http://www.garlikov.com/philosophy/slope.htm (assessed on 12/03/2009, 13:00).