1. Inouye and Hirasawa, J. Tokyo Chem. Soc., 39, 300 (1918).
2. Anon., J. Soc. Chem. Indust. Japan, 32, 257 (1929).
3. Nicolet and Saidel, J. Biol. Chem., 139, 477 (1941).
4. Lang, Biochem. Z., 319, 283 (1948).
5. Kodama, Biochem. J., 20, 1208 (1926).