Marchand, E.W. (1987) Gradient Index Optics. Academic Press, New York.
 Gordon, J.M. (2000) Spherical Gradient Index Lenses as Perfect Imaging and Maximum Power Transfer Devices. Applied Optics, 39, 3825-3831.
 Wade, R.K., Hunter, B.V., Walters, B. and Fournier, P. (1998) Properties, Specifications, and Tolerances of Radium Glasses. Light Path technologies, Inc., 6820, Academy Parkway e., NE, Albuquerque.
 Jpn, J. (1998) Design of Imaging Lens Systems That Use Low Dispersive Radial Gradient-Index Rod. Japanese Journal of Applied Physics, 37, 3633-3637.
 Crawford, M.K. (2000) Tolerance Analysis of Axial Gradient-Index Lenses. Ph.D. Thesis, The University of Rochester, Rochester, NY. Source DAI-B 61/02, p 914, 188 pages. 34.
 Moore, D.T. (1974) Gradient Index Optics: Aspects of Design, Testing, Tolerancing, and Fabrication. Ph.D. Thesis, Rochester Univ., NY.
 Wang, Y.-Z. and Wang, X. (1997) Improvements on the Ray Tracing Procedure for High-Order Aspheric Surfaces. Optical Engineering, 36, 2259-2260.
 Kingslake, R. (1989) A History of the Photographic Lens. Academic Press, New York.
 Kingslake, R. (1983) Lens Design Fundamentals. Academic Press, New York.
 U.S Government Printing Office (1962) Military Standardization Hand Book: Optical Design, MIL-HDBK-141.5. U.S Government Printing Office, Washington DC.
 Foreman Jr., J.W. (1974) Computation of RMS Spot Radii by Ray Tracing. Applied Optics, 13, 2585-2588.
 Sharma, A., Kumar, D.V. and Ghatak, A.K. (1982) Tracing Rays through Gradient-Index Media: A New Method. Applied Optics, 21, 984-987.
 Stone, B.D. and Forbes, G.W. (1990) Optimal Interpolants for Runge-Kutta Ray Tracing in Inhomogeneous Media. Optical Society of America, Washington DC.
 ZEMAX (2001) Optical Design Program—Version 10.0. Focus Software, Incorporated, Arizon.
 Born, M. and Wolf, E. (1980) Principle of Optics. 6th Edition, Pergaman Press, Oxford.
 Fisher, D.J., Harkrider, C.J. and Moore, D.T. (2000) Design and Manufacture of Gradient-Index Axion. Applied Optics, 39, 2687-2693.
 Krishna, K.S.R. and Sharma, A. (1996) Low-Power Gradient-Index Microscope Objective: Design. Applied Optics, 35, No.28,.
 Al-Hajaji, H.A.A. (2003) The Characteristics of Rays Paths in a GRIN Medium. Thesis, Um-Al-qura University, Mecca.
 Mayer-Arendt, J.R. (1972) Introduction to Classical and Modern Optics. Prentice-Hall, INC., Englewood Cliffs.