1. R. Penrose, The Structure of Space-Time [Russian translation], Mir, Moscow (1972).
2. S. Hawking and G. Ellis, The Large Scale Structure of Space-Time, Cambridge University Press, Moscow (1975).
3. L. D. Landau and E. M. Lifshits, Field Theory [in Russian], Nauka, Moscow (1988), ff. 119, 94.
4. A. Einstein, Collected Scientific Works [Russian translation], Vol. 2, Nauka, Moscow (1966), p. 353.
5. I. L. Zhogin, Izv. Vyssh. Uchebn. Zaved., Fiz., No. 9, 47; No. 2, 22 (1991).