1. Arnold, V.: 1976,Les M�thodes Math�matiques de la M�canique Classique, NAUKA, Moscou, Chap.6.
2. Byrd, P.F. and Friedman, M.D.: 1971,Handbook of Elliptic Integrals for Engineers and Physicists, Springer-Verlag, Berlin.
3. French, R.G., Elliot, J.L., Levine, S.E.: 1986,Icarus 67, 134.
4. Goldreich, P.: 1965,Astron.J. 70, 5.
5. Hori, G.: 1979, in Nomura, T., ed(s).,12 th ISAS Lunar and Planetary Symposium, Institute of Space and Astronautical Science, Tokyo, 166?170.