1. C.H. Townes, in Quantum Electronics, edited by C.H. Townes (Columbia University Press, New York, 1960) pp. vi-viii.
2. C.H. Townes, ibid., pp. 405–409.
3. C.H. Townes, in Advances in Quantum Electronics, edited by J.R. Singer ( Columbia University Press, New York, 1961 ) pp. 3 – 11.
4. I. L. Fabelinskii, Molecular Scattering of Light (Plenum Press, New York, 1968) and references therein.
5. D. H. Rank, J. M. McCortney, and J. Szaz, J. Opt. Soc. Amer. 38, 287 (1948).