1. S. Hawking andR. Penrose:Proc. Roy. Soc., A314, 529 (1970) and related papers cited in the references.
2. V. A. Belinskii andI. M. Khalatnikov:Sov. Phys. JETP,30, 1174 (1970) and carlier papers cited in the references.C. W. Misner:Phys. Rev. Lett.,22, 1071 (1969).
3. D. Eardley, E. Liang andR. Sachs:Journ. Math. Phys.,23, 99 (1972).
4. See, for example,B. Godfrey:Static, axisymmetric vacuum metrics, Ph. D. thesis, Princeton University (1970, unpublished).
5. G. Erez andN. Rosen:Bull. Res. Coun. of Israel, F8, 47 (1959).