1. F. Zernike, Physica 9, 686 (1942).
2. J. Goodman, Introduction to Fourier Optics (McGraw-Hill, San Francisco, 1968).
3. M. Franson, Phase-Contrast and Interference Microscope (Nauka, Moscow, 1954) [in Russian].
4. M. A. Vorontsov, M. A. Koryabin, and V. I. Shmal’gauzen, Controlled Optical Systems (Nauka, Moscow, 1988) [in Russian].
5. J. Glückstad and D. Palima, Generalized Phase Contrast: Applications in Optics and Photonics (Springer, Dordrecht, 2009), p.315.