1. A. A. Gershun, Selected Works on Photometry [in Russian], GIFNL, Moscow (1958); M. M. Gurevich, Trudy GOI,6, No. 1, 657 (1931).
2. Laser-Design Methods [in Russian], Vol. 1, Izd. Nauka i Tekhnika, Minsk (1966);
3. B. I. Stepanov and V. P. Gribkovskii, Introduction of the Theory of Luminescence [in Russian], Izd. AN BSSR, Minsk (1963).
4. K. S. Shifrin, Light Scattering in a Turbid Medium [in Russian], GITTL, Moscow-Leningrad (1951); V. V. Sobolev, Radiation Transport in Stellar and Planetary Atmospheres [in Russian] (1956).
5. R. W. Ditchburn, Light, Interscience, New York (1964).