1. Dewey J. How we think. Buffalo, NY: Prometheus Books, 1910:16.
2. Lasswell HD, Kaplan A. Power and society: a framework for political inquiry. New Haven: Yale University Press, 1950:xv–xvi.
3. Rayner S, Malone EL, editors. Human choice and climate change. Columbus, Ohio: Battelle Press, 1998.
4. Sherden WA. The fortune sellers: the big business of buying and selling predictions. New York: John Wiley and Sons, 1998.
5. Hempel CG. Philosophy of natural science. Englewood Cliffs, NJ: Prentice-Hall, 1966.