1. J. M. Ziman, “Electrons and Phonons”, Oxford University Press (London 1960).
2. M. Born and K. Huang, “Dynamical Theory of Crystal Lattices”, Clarendon Press (Oxford 1954).
3. C. P. Enz, “Electron-Phonon and Phonon-Phonon Interactions”, in “Theory of Condensed Matter”, International Atomic Energy Agency (Vienna 1968) pp. 729–782.
4. C. P. Enz, Ann. Phys. (N.Y.) 46, 114 (1968).
5. See ref. 2, § 14 and ref. 3, p. 736.