1. Krinov, E. L., The Solar System, edit. by Middlehurst, B. M., and Kuiper, G. P., 4, 208 (Univ. Chicago Press, 1963).
2. Kulik, L. A., Akademiia Nauk S.S.S.R., Co. R. (Doklady), No. 23, 399 (1927).
3. Told to Kulik, L. A., on March 30, 1927. See ref. 2.
4. Kulik, L. A., Trans. Lomonosov Inst. Akad. Sci. (U.S.S.R.), 2, 73 (1932).
5. Fesenkov, V. G., Astronomicheskii Zhurnal, 38, No. 4, 577 (1961).