1. The book by David Katz is Der Aufbau der Farbwelt, 1911. It has been published in England as The World of Colour, Kegan, Paul, Trench, Trubner, London, 1935.
2. The book by the Optical Society of America-Committee on Colorimetry is The Science of Color, Crowell, New York, 1953.
3. The Perception of Color, Wiley, New York, 1974, p. 90.
4. The Language of Architecture, Studentlitteratur, Lund, Sweden, 1967, p. 50.
5. Ref. 3, p. 53.