1. D. Ruelle andF. Takens:Commun. Math. Phys.,20, 167 (1971);23, 343 (1971);64, 35 (1978).
2. S. Smale:Bull. Am. Math. Soc.,73, 747 (1967).
3. E. N. Lorentz:J. Atmos. Sci.,20, 130 (1963).
4. C. L. Siegel:Nachr. Akad. Wiss. Gott. Math. Phys. Kl., 21 (1952);A. N. Kolmogorov:Dokl. Akad. Nauk SSSR,98 (4), 527 (1954);J. Moser:Akad. Wiss. Gott. Math. Phys. Kl., IIa, No. 1, 1 (1962);V. I. Arnol’d:Russ. Math. Surv.,18 (5), 9 (1963);18 (6), 91 (1963). See alsoC. L. Siegel andJ. Moser:Lectures on Celestial Mechanics (Berlin, 1971);J. Moser:Stable and Random Motions in Dynamical Systems (Princeton, N. J., 1973);V. I. Arnol’d andA. Avez:Ergodic Problems of Classical Mechanics (New York, N. Y., and Amsterdam, 1968).
5. G. Contopoulos:Astron. J.,68, 1 (1963);M. Hénon andC. Heiles:Astron. J.,69, 73 (1964);C. Froeschlé:Astrophys. Space Sci.,14, 110 (1971).