1. Clausius, R. The Mechanical Theory of Heat (MacMillan, London, 1879).
2. Callen, H. B. Thermodynamics and an Introduction to Thermostatistics (Wiley, New York, 1985).
3. Boltzmann, L. On the relation of a general mechanical theorem to the second law of thermodynamics. Sitz. Akad. Wiss. Vienna, part II 75, 67–73 (1877).
4. Lebowitz, J. L. Boltzmann’s entropy and time’s arrow. Phys. Today 46, 32–38 (1993).
5. Zeh, H. D. The Physical Basis of the Direction of Time (Springer, Berlin, 2007).