\begin{thebibliography}{1}

\bibitem{Bekenstein81}
J.~Bekenstein.
\newblock {\em Phys Rev D 23}, 287, 1981.

\bibitem{Misner73}
C.~Misner, K.~Thorne, and J.~Wheeler.
\newblock {\em Gravitation}.
\newblock W. Freeman \& Co, 1973.

\bibitem{Tipler94}
F.~Tipler.
\newblock {\em The Physics of Immortality}.
\newblock Macmillan, London, 1994.

\end{thebibliography}
