1. ASTM, American Society for Testing and Materials: Standard Terminology of Appearance. Standard E 284-01. ASTM, West Conshohocken (2001)
2. CIE, Commission Internationale de l’Eclairage, Technical Committee 1-65: CIE Technical Report: A Framework for the Measurement of Visual Appearance. CIE Central Bureau, Viena (2006)
3. Katz, D.: Der Aufbau Der Farbwelt, 2nd ed. of Die Erscheinungsweisen Der Farben Und Ihre Beeinflussung Durch Die Individuelle Erfahrung. Johann Ambrosius Barth, Leipzig (1911/1930). English translation by MacLeod, R.B., Fox, C.W.: The World of Colour. Keagan Paul, Trench, Trubner, London (1935)
4. Pope, A.: The Language of Drawing and Painting. Harvard University Press, Cambridge, MA (1949)
5. Optical Society of America, Committee on Colorimetry: The Science of Color. Crowell, New York (1953). chapter 2