1. H. U. Bergmeyer, “Methods of Enzymatic Analysis,” Vol. 3, 2nd Ed., ed. by H. U. Bergmeyer, Academic Press Inc., New York and London, 1974, p. 1323.
2. Y. Ota, “Handbook of Microbiology,” Vol. 111, ed. by A. I. Laskin and H. A. Lechevalier, CRC Press, Inc., Cleveland, Ohio, 1973, p. 625.