1. Loschmidt, J., S.B. Akad. Wiss. Wein, 73, 139 (1876).
2. Penrose, O., and Percival, I. C., Proc. Phys. Soc., 79, 606 (1962).
3. Landau, L. D., and Lifshitz, E. M., Statistical Physics, 28 (Pergamon Press, Oxford, 1969).
4. Landsberg, P. T., Studium Generate, 23, 1108 (1970).
5. Proc. Intern. Conf. Thermodynamics, Cardiff, 1970 (edit. by Landsberg, P. T.) (Butterworths, London, 1970).