1. C. D. Hodgman, R. S. Weast, R. S. Shaukland and S. M. Selly, “Handbook of Chemistry and Physics,” Chemical Rubber Publishing Co., Cleveland, Ohio, U.S.A., 1962, pp. 2614~2615.
2. E. J. Cohn and J. T. Edsall, “Proteins, Amino Acids and Peptides as Ions and Dipolar Ions,” Reinhold Publishing Corp., New York, N.Y., 1943, Chapter 9.