1. J. von Neumann, Mathematical Foundations of Quantum Mechanics, Princeton (1955).
2. R. J. Glauber, Phys. Rev.,130, 2529;131, 2766 (1963).
3. J. R. Klauder and E. C. Sudarshan, Fundamentals of Quantum Optics, Benjamin, New York (1968).
4. B. Ya. Zel'dovich, A. M. Perelomov, and V. S. Popov, Zh. Eksp. Teor. Fiz.,55, 589 (1968); 57, 196 (1969); Preprints Nos. 612, 618 [in Russian], ITEF (1968).
5. M. V. Terent'ev, Preprint No. 773 [in Russian], ITEF (1970).