1. Carter, B. (1968).Phys. Rev.,174, 1559.
2. Sharp, N. A. (1979).Gen. Rel. Grav.,10, 659.
3. Chandrasekhar, S. (1983).The Mathematical Theory of Black Holes (Oxford University Press, Oxford).
4. Anderson, J. et al. (1982).Proceedings of the Second Marcel Grossmann Meeting on General Relativity, R. Ruffini, ed. (North-Holland, New York), p. 939.
5. van Patten, R. A., and Everitt, C. W. F. (1976).Phys. Rev. Lett.,336, 629.