1. Feynman, R. (1992) The Character of Physical Law, Penguin books edition, with Introduction by Paul Davies; the original edition published in 1965
2. Hartle, J. B., Hawking, S. W. (1983) Wave function of the Universe, Phys. Rev. D28, 2960. For more recent developments, see Page, D. N. (1991) Minisuperspaces with conformally and minimally coupled scalar fields, J. Math. Phys. 32, 3427, and references therein
3. Kuchař, K. V. (1994) private communication based on unpublished calculations. See also Peleg, Y. (1995) The spectrum of quantum dust black holes, Phys. Lett. B356, 462
4. Chandrasekhar, S. (1987) Ellipsoidal Figures of Equilibrium, Dover paperback edition, Dover Publ., Mineola, N. Y.
5. Tassoul, J.-L. (1978) Theory of Rotating Stars, Princeton University Press, Princeton, N. J.