1. Kopal, Z., and Millns, P. Y., “Astronomical Optics and Related Subjects”, 389 (North Holland Pub. Co., Amsterdam, 1956).
2. Bowen, E. J., “The Chemical Aspects of Light”, 279 (Clarendon Press, Oxford, 1946).
3. Barnes, B. T., and Forsythe, W. E., J. Opt. Soc. Amer., 27, 83 (1937).
4. B. T. H. Technical Publication, DL9514–2, edit. 2 (Jan. 1955).