1. The best accounts of this subject are: Zwonkin, A.K., Levin, L.A., Usp. Mat. Naouk 25, 85, 1970 Dellacherie, C., Gazette des mathématiciens n°11, 1978 Alekseev, V.M., Yakobson, M.V., Phys. Reports, 75, 287, 1981 Popular accounts are given in Ford, J., Physics Today, 40, April
2. See for example the special issues of International J. of Theor. Physics (1982) devoted to the proceedings of a conference on “Physics of Computation”
3. Berry, M.V., in Jorna, S., ed. Topics in non linear dynamics Am. Inst, of Physics; 1978
4. Helleman, R.H.G., in Cohen, E.G.D., ed. Fundamental problems in statistical mechanics vol.5, North-Holland 1980
5. Planck, M., Verhandl. Dtsch. phys. Ges. 13, 138, 1911