1. J. Sahade and O. E. Ferrer, Publ. Astron. Soc. Pac.,94, 113 (1982).
2. G. A. Gurzadyan, Astrophys. Space Sci.,80, 189 (1981).
3. V. V. Sobolev, Course of Theoretical Astrophysics [in Russian], Nauka, Moscow (1985).
4. D. G. Hummer, JILA Rep. No. 24, Boulder, Colorado (1964).
5. M. A. Arakelyan, Astrofizika,5, 75 (1969).