1. V. V. Ivanov, Radiative Transfer and the Spectra of Celestial Bodies [in Russian], Nauka, Moscow (1969).
2. M. M. Basko, Preprint No. 410 [in Russian], Institute of Cosmic Research, USSR Academy of Sciences (1978).
3. C. van Trigt, Phys. Rev., A13, 734 (1976).
4. M. M. Basko, Zh. Eksp. Teor. Fiz.,75, 1278 (1978).
5. H. Frisch, Preprint No. 1131, Center for Astrophysics (1979).