1. 2) (a) H. Zollinger, “Color Chemistry: Syntheses, Properties, and Applications of Organic Dyes and Pigments 2nd Ed”, VCH Weinheim, New York, Basel, Cambridge, 1991, p4
2. (b) A. B. Greenfield, “A Perfect Red: Empire, Espionage, and the Quest for the Color of Desire” Harpe, 2005
3. 4) Z. Yoshida, T. Kitao, “Chemistry of Functional Dyes”, MITA PRESS, Tokyo Japan, 1989