1. AMS (U.S. Army Map Service, Washington, D.C.): 1964, Tech. Rept. No. 29, part 2.
2. Arthur, D. W. J.: 1965,Comm. Lunar Planetary Labor., Tucson Nos. 62 and 89.
3. Bystrov, N. F.: 1972,Publ. 18th Astron. Conf. U.S.S.R., p. 327.
4. Eichhorn, von Wurmb, H., Googe, W. D., Lukac, C. F., and Murphy, J. K.: 1970,Mem. Roy. Astron. Soc. 73, Part 2.
5. Franz, J.: 1901,Mitt. Sternwarte Breslau, No. 1.