1. ASTM. Visual appraisal of color differences of diffusely-illuminated opaque material, 1996. ASTM D 1729.
2. Colour Physics for Industry. Bradford, Great Britain: Society of Dyers and Colourists; 1997.
3. CIE. Colorimetry, 2nd edition. Paris: Central Bureau of the CIE; 1986. CIE pub 15.2–1986.
4. Visual Assessment and Practical Colorimetry in the Plastics Industry. Leverkusen, Germany: Bayer AG; 1994.
5. Billmeyer and Saltzman's Principles of Color Technology. New York: Wiley; 2000.