1. M. Scully:Quantum Optics, edited byR. J. Glauber (New York, N. Y., 1969), p. 586.
2. R. J. Glauber:Quantum Optics and Electronics, edited byC. DeWitt et al. (New York, N. Y., 1965), p. 63.
3. A. Perina:Quantum Optics, edited byS. M. Kay andA. Maitland (New York, N. Y., 1970), p. 515, has derived a similar expression for a many-mode case, asking for the probability to be in a state ‖{n λ}> with $$\sum\limits_\lambda {n_\lambda = n} $$ .
4. Perina (3):Quantum Optics, edited byS. M. Kay andA. Maitland (New York, the statistical properties of photons themselves. We feel that, as a general statement, this may not be valid.
5. I am indebted to Dr.E. Holzherr for this last equation.