1. Andoyer, H.: 1903,Bull. Astron. 20, 321?356.
2. Arnol'd, V. I. and Avez, A.: 1968,Ergodic Problems of Classical Mechanics, W. A. Benjamin, New York.
3. Brouwer, D.: 1963,Astron. J. 68, 152?159.
4. Brown, H., Goddard, I., and Kane, J.: 1967,Astrophys. J. Suppl. 16, 57?123.
5. Giffen, R.: 1973,Astron. Astrophys. 23, 387?403.