1. Porter, J. N., Hewitt, R. I., Hesseltine, C. W., Krupka, G., Lowery, J. A., Wallace, W. S., Bohonos, N., and Williams, J. H., Antibiot. and Chemother., 2, 409 (1952).
2. Takeda, Y., Hayashi, S., Nakagawa, H., and Suzuki, F., J. Biochem., 48, 169 (1960).
3. Hultin, T., Experientia, 17, 410 (1961).
4. Ferguson, J. J., Biochim. Biophys. Acta, 57, 616 (1962).
5. Nemeth, A. M., and de la Haba, G. L., J. Biol. Chem., 237, 1190 (1962).