1. Zernike, F.,Physica, 1, 689 (1934).
2. Nijboer, B. R. A., “The Diffraction Theory of Aberrations,” Groningen thesis, 1942. For the experimental part, see the thesis by Nienhuis, K., Groningen, 1948. For microwave experiments see: Bachynski, M. P. and Bekefi, G.,IRE Trans., A.4, No. 3, 412 (1955).
3. Nijboer, B. R. A. A., “Studies in Microwave Optics,” McGill Univ. Tech. Rept., 38 (1957).
4. Steward, G. C., “The Symmetrical Optical System,” Cambridge, Cambridge Univ. Press, 1928.
5. Picht, Johannes, “Optische Abbildung,” Braunschweig, 1931.