1. Ya. B. Zeldovich andI. D. Novikov:Relativistic Astrophysics (Chicago, 1971).
2. Suggested byJ. A. Wheeler atWilliam H. Fowler Celebration Conference at the Institute of Theoretical Astrophysics, Cambridge University, July 13, 1971 (unpublished).
3. M. Davis, R. Ruffini, J. Tiomno andF. Zerilli:Phys. Rev. Lett.,28, 1352 (1972), and references quoted therein.
4. J. Tiomno andR. Ruffini: to be published.
5. R. Ruffini, J. Tiomno andC. V. Vishveshwara:Lett. Nuovo Cimento,3, 211 (1972) here to be referred to as I.