1. Achenbach, J.D.: Wave Propagation in Elastic Solids. North-Holland, Amsterdam (1973)
2. Ali, M.H., Rahman, M.A.: Int. J. Theor. Phys. 48, 1717 (2009)
3. Arnowitt, R., Deser, S., Misner, C.W.: Gravitation: An Introduction to Current Research. Wiley, New York (1962)
4. Bahcall, N.A., Ostriker, J.P., Perlmutter, S., Steinhardt, P.J.: Science 284, 1481 (1999)
5. Buzzi, V., Hines, K.C., Treumann, R.A.: Phys. Rev. D 51, 6663 (1995a)