Uriel Levy, Mendlovic, David , and Zalevsky, Zeev . 1/20/1998. “On-Axis Phase Only Computer Generated Holograms Based On Minimal Etching Process”. Journal Of Modern Optics, 45, 7, Pp. 1437-1449. https://www.tandfonline.com/doi/abs/10.1080/09500349808230639.