1. Obata, Y., and Horitsu, H., J. Agr. Chem. Soc., Japan, 32, 615 (1958).
2. Kuroiwa, Y., Hashimoto, H., and Nakagawa, K., Agr. Biol. Chem., 25, 427 (1961).
3. Obata, Y., Koshika, M., and Tanaka, H., Nature, 190, 635 (1961).
4. Obata, Y., Koshika, M., and Tanaka, H., Agr. Biol. Chem., 25, 588 (1961).
5. Kuroiwa, Y., and Hashimoto, N., Amer. Soc. Brewing Chemists Proc., 28 (1961)