1. D'Eath, P. D. (1975).Phys. Rev. D,12, 2183?2199.
2. D'Eath, P. D. (1978).Phys. Rev. D, (in press).
3. Matzner, R. A., and Nutku, Y. (1974).Proc. Roy. Soc. A336, 285?305.
4. Smarr, L. (1975).The Structure of General Relativity with a Numerical Illustration: The Collison of Two Black Holes. Ph.D. Thesis, University of Texas at Austin.
5. Curtis, G. E. (1975).Twistor Theory and the Collision of Plane-Fronted Impulsive Gravitational Waves. D. Phil. Thesis, Oxford University.