1. Quoted by Parr, R. G.: Proc. Nat. Acad. Sci. U.S.A. 72, 763 (1975)
2. Venkataraman, K.: The Chemistry of Synthetic Dyes, Vol. l, Chap. 8, p. 323. New York: Academic Press 1952
3. Smiles, S.: The Relations between Chemical Constitution and some Physical Properties, Chap. 10, p. 324. London: Longmans Green and Co. 1910
4. Werner, A.: Liebigs Ann. Chem. 386, 31 (1911)
5. Tsuchida, R.: Bull. Chem. Soc. Japan 13, 388, 436, and 471 (1938); Yamada, S., Tsuchida, R.: Bull. Chem. Soc. Japan 26, 15 (1953)