1. J. L. Olsen, Electron Transport in Metals, Interscience, New York, 1962.
2. M. Born, Atomic Physics, Blackie, London, 1962, chapter 8.
3. D. ter Haar, Elements of Statistical Mechanics, Rinehart, New York, 1954, chapter 4.
4. C. Kittel, Solid State Physics, Wiley, New York, 1956, chapters 11 and 13.
5. A. J. Dekker, Solid State Physics, Prentice-Hall, New York, 1957, chapters 10 and 13.