1. G. Esposito, Quantum Gravity, Quantum Cosmology, and Lorentzian Geometries (Springer-Verlag, 1992).
2. S. Weinberg, Gravitation and Cosmology. Principles and Applications of the General Theory of Relativity (Wiley, 1972).
3. Ch. W. Misner, K. S. Thorne, and J. A. Wheeler, Gravitation (Freeman and Company, 1973).
4. P. A. M. Dirac, Generalized Hamiltonian Dynamics, Proc. Roy. Soc. (London) A 246, 326 (1958).
5. D. M. Gitman and I. V. Tyutin, Quantization of Fields with Constraints (Springer-Verlag, 1990).