1. E. Fermi,Phys. Rev. 15:1169 (1949).
2. I. Percival and D. Richards,Introduction to Dynamics (Cambridge University, Cambridge, 1982).
3. S. Ulam, InProceedings 4th Berkeley Symposium on Mathematical Statistics and Probability (University of California Press, 1961), Vol. 3, p. 315.
4. A. J. Lichtenberg and M. A. Lieberman,Phys. Rev. A 5:1852 (1972).
5. A. J. Lichtenberg and M. A. Lieberman,Physica 1D:291 (1980).