1. R J Glauber, Phys. Rev. 131, 2766 (1963)
2. W H Louisell, Quantum statistical properties of radiation (Wiley, New York, 1973)
3. D F Walls and G J Milburn, Quantum optics (Springer-Verlag, Berlin, 1994)
4. S Y Zhu, M S Zubairy and M O Scully, Frontiers of quantum optics and laser physics, Springer, Proc. Inter. Conference (Hong Kong, Baptist Univ., 1997)
5. M Boiteux and A Levelut, J. Phys. A6, 589 (1973)