1. J. R. Verner, Proc. SPIE, 25, 239 (1971)
2. J. C. Wyant, in Space Optics: Proc. IX Congress of ICO (US National Academy of Sciences, Wash. DC. 1974) p. 643
3. M. Born and E. Wolf, ‘Principles of Optics* (Pergamon Press, 1965) p. 467
4. J. Pastor, Appl. Opt., 8 525 (1969)
5. J. Pastor, J. S. Harris and G. E. Evans, J. O. S. A., 58, 1556A (1968)