1. Clotfelter, Charles, and Philip Cook, (1989).Selling Hope: State Lotteries in America. Cambridge: Harvard University Press.
2. Cohen, John, and E.I. Chesnick (1970). “The Doctrine of Psychological Chances”,British Journal of Psychology, pp. 323–334.
3. Cohen, John (1960).Chance, Skill and Luck: The Psychology of Guessing and Gambling. London: Penguin Books.
4. Harte, Bret (1896).The Writings of Bret Harte, Vol. 2, pp. 66–83. New York: Houghton Mifflin.
5. Holroyd, F. & Collings, S. (1990). The calculated risk. In J. Dowie (ed.)Risk and rationality. Milton Keynes, United Kingdom: The Open University Press.