1. J. M. Ziman, Principles of Solid State Theory (Cambridge University Press, Cambridge, 1971), pp. 110, 111.
2. K. Yamasaki, J. Phys. Soc. Jpn. 17, 1262 (1962).
3. F. Vovelle and G. C. Dumas, Mol. Phys. 34, 1661 (1977).
4. H. G. Drickamer, R. W. Lynch, R. L. Clendenen, and E. A. Perez-Albuerne, Solid State Physics (Academic, New York, 1966), Vol. 19, p. 135.
5. V. R. Regel, A. I. Slutsker, and E. E. Tomashevskii, Kinetic Nature of the Strength of Solids (Nauka, Moscow, 1974) [in Russian].