Gibbons G. and Hawking S. ed. Euclidean Quantum Gravity. Singapore: World Scientific Publishing Company, 1993.
290
Hawking S.Hawking on the Big Bang and Black Holes. Singapore: World Scientific Publishing Company, 1993.
291
Hawking S.The No-Boundary Proposal and the Arrow of Time. Halliwell J., Perez-Mercader J. and Zurek W. eds. Physical Origins of Time Asymmetry. Cambridge: Cambridge University Press, 1992. p. 268.
