1. I. D. Dow and D. Redfield, Phys. Rev.,B5, No. 2.
2. V. L. Bonch-Bruevich, A. G. Mironov, and J. P. Zviagin, Nuovo Cimento,3, No. 4, 32 (1973).
3. V. L. Bonch-Bruevich, Phys. Status Solidi,42, 35 (1970).
4. V. L. Bonch-Bruevich, in: Statistical Physics and Quantum Field Theory [in Russian], N. N. Bogolyubov (editor), Nauka, Moscow (1973), p. 337.
5. T. F. Mazets and S. K. Pavlov, in: The Structure and Properties of Noncrystalline Semiconductors [in Russian], Nauka, Leningrad (1976), p. 260.