1. Brown, E. W.: 1919, inTables of the Motion of the Moon, Yale Univ. Press, New Haven, Conn.
2. Eigen, J. M. and Hathaway, J. D.: 1967, inMeasure of the Moon (ed. by Z. Kopal and C. L. Goudas), D. Reidel Publ. Co., Dordrecht, Holland; pp. 305?316.
3. Gorynia, A. A.: 1965, Nauch. Dumka, Ser. Astron.-Astrofiz., Kiev.
4. Habibullin, Sh. T.: 1966, Trudy Astron. Inst. Univ. Kazan, No. 34.
5. Jeffreys, H.: 1924, inThe Earth (and later editions) Chapter 4.