1. Velasquez M. Business ethics: concepts and cases, 4th edition. Upper Saddle River NJ: Prentice Hall; 1998.
2. Plato. Crito. In Five dialogues. Grube GMA; trans. Indianapolis: Hackett Publishing; 1981.
3. Fried C. Contract as promise: a theory of contractual obligation. Cambridge: Harvard University Press; 1981.
4. Austin JL. How to do things with words. Cambridge: Harvard University Press; 1962.
5. Austin JL. Performative utterances. In Philosophical papers. Urmson JO and Warnock GJ; eds. Cambridge: Oxford University Press; 1970b.