1. Matzner, R. A., and Misner, C. W. (1967).Phys. Rev. 154, 1229; Misner, C. W. (1978).Phys. Rev. D 18, 4510.
2. Sánchez, N. (1982).Phys. Rev. D 26, 2589.
3. Neugebauer, G. and Kramer D. (1984). InClassical General Relativity, W. Bonnor, Jamal N. Islam, M. A. H. MacCallum, eds. (Cambridge University Press, Cambridge).
4. Belinsky, V. A., and Zakharov, V. E. (1978).Zh. Eksp. Teor. Fit. 75 1953.
5. Whitman, A. P., and Stoeger, W. R. (1992).Gen. Rel. Grav. 24, 641.