1. Bridgman P W 1961 The Nature of thermodynamics (University Press: Cambridge, Mass p. 169
2. Casper B M and Freier S 1973 Am. J. Phys. 41 509
3. Ehrenfest O P and Trkal V 1921 Ann. Physik 65 609
4. Fong P 1963 Foundations of thermodynamics (New York: Oxford University Press)
5. Fowler R H 1966 Statistical mechanics (London: Cambridge University Press) pp. 205–206