1. S. V. Vavilov, A. A. Gippius, and E. A. Konorova, Electronic and Optical Properties of Diamond (Nauka, Moscow, 1985).
2. V. K. Bazhenov, I. M. Vikulin, and A. G. Gontar’, Fiz. Tekh. Poluprovodn. (Leningrad) 19, 1345 (1985) [Sov. Phys. Semicond. 19, 829 (1985)].
3. V. V. Sobolev, Intrinsic Energy Levels of Solids Belonging to Group IVA (Shtiintsa, Kishinev, 1978).
4. A. A. Levin, Fiz. Tekh. Poluprovodn. (Leningrad) 3, 1864 (1969) [Sov. Phys. Semicond. 3, 1579 (1969)].
5. F. German, R. L. Kortum, and C. D. Kuglin, Int. J. Quantum Chem., Symp. 1, 533 (1967).