1. G. H. Hardy, J. E. Littlewood, and G. Polya, Inequalities, Cambridge (1952).
2. R. Glauber, in: Quantum Optics and Quantum Radiophysics [Russian translation], Mir (1966).
3. V. Ya. Anisimov and B. A. Sotskii, Teor. Mat. Fiz.,14, 282 (1973).
4. K. E. Cahill and R. J. Glauber, Phys. Rev.,177, 1882 (1969).
5. V. Ya. Anisimov and B. A. Sotskii, Dokl. Akad Nauk BSSR,18, 210 (1974).