1. Runeckles, V. C., and Krotkov, G., Arch. Biochem. Biophys., 70, 442 (1957).
2. Barnard, P. W. C., Bunton, C. A., Llewellyn, D. R., Oldham, K. G., Silver, B. L., and Vernon, C. A., Chem. and Indust., 760 (1955).
3. Szulmajster, J., Grunberg-Manago, M., and Aubel, E., Bull. Soc. Chim. Biol., 35, 455 (1953).