1. H. Haken, Synergetics, an introduction (Springer, Berlin, 1983), chapt. 7.
2. R.P. Lippmann, IEEE ASSP Mag., p. 4, April (1987). 61
3. L.A. Zadeh, Fuzzy sets and applications ( Wiley, New York, 1987 ).
4. J.H. Holland, Adaptation in natural and neural systems ( Univ. of Michigan Press, Ann Arbor, 1975 ).
5. C.G. Langton in Artificial life, edited by C.G. Langton. ( Addison-Wesley, Redwood City, CA 1989 ).