====== Bibliografia ======
  * Thermal Physics, Daniel V. Schroeder, Addison Wesley (1999).
  * Thermodynamics and an Introduction to Thermostatistics, H. B. Callen, Wiley, New York, (1985).
  * An introduction to Thermodynamics and Statistical Mechanics Thermal Physics, Keith Stowe, Cambridge (2007).
  * Fundamentals of Statistical and Thermal Physics, F. Reif, McGraw-Hill, New York, 1965.