1. Bray, T. A. and Goudas, C. L.: 1967, in Z. Kopal (ed.),Adv. Astron. Astrophys. Vol.5, pp. 72?130, Acad. Press, New York.
2. Goudas, C. L.: 1961,Bull. Soc. Math. Gr�ce, Nouvelle Serie.,2, 1.
3. Hadjidemetriou, J.: 1975,Celest. Mech. 12, 267.
4. H�non, M.: 1973,Astron. Astrophys. 28, 415.
5. H�non, M.: 1976,Celest. Mech. 13, 277.