1. D. Christodoulou andR. Ruffini:Phys. Rev., in press.
2. D. Christodoulou andR. Ruffini:Back Holes, the largest-energy storehouse in the Universe, inGravity Foundation, 1971, in press.
3. F. Zerilli:Phys. Rev. D.,2, 2141 (1970).
4. M. Davis andR. Ruffini:Lett. Nuovo Cimento, in press.
5. M. Davis, R. Ruffini, W. Press andR. Price:Phys. Rev. Lett.,21, 1466 (1971).