1. P. Painlevé, Bull. Soc. Math. France,28, 201 (1900).
2. P. Painlevé, Acta Math.,25, 1 (1902).
3. W. F. Osgood, ?Topics in the Theory of Functions of Several Complex Variables? (?The Madison Colloquium, 1913, Part II?, American Mathematical Society, Rhode Island, 1914). Reprinted. Dover, New York, 1966.
4. R. S. Ward, Phys. Lett. A,102, 279 (1984).
5. J. Weiss, M. Tabor, and G. Carnevale, J. Math. Phys.,24, 522 (1983).