1. Colgate, S.A. and White, R.H. (1966).Astrophys. J.,143, 626?681.
2. Kuchowicz, B. (1972).The Cosmic v, (Nuclear Energy Information Centre, Warsaw).
3. Misner, C.W. (1965).Phys. Rev.,B137, 1360?1364.
4. Bonnor, W.B. (1962). InRecent Developments in General Relativity, (Pergamon Press, London and New York), pp. 167?169.
5. Hoffmann, B. (1932).Q.J. Math.,3, 226?237.