1. R. Penrose, The Emperor’s New Mind, New York: Penguin Books, 1989.
2. John L. Casti, Alternate Realities: Mathematical Models of Nature and Man, New York, John Wiley and Sons, 1989.
3. D. Botkin, Life and Death in a Forest: The Computer as an Aid to Understanding, in: C. Hall and J. Day (eds.), Ecosystem Modeling in Theory and Practice: An Introduction with Case Studies, New York: John Wiley and Sons, 1977, p. 217.
4. A. Lightman and O. Gingerich, When Do Anomalies Begin?, Science 255:690–695, 1991.
5. For an excellent summary of this argument, see P. Denning, Modeling Reality, American Scientist 78:495–498, 1990.