1. Silvestroni, E., and Bianco, I., Nature, 191, 1208 (1961).
2. Itano, H. A., and Robinson, E., Nature, 183, 1799 (1959).
3. Gammack, D. B., Huehns, E. R., Lehmann, H., and Shooter, E. M., Biochem. J., 76, 55, P (1960).
4. Bianco, I., Modiano, G., Bottini, E., and Lucci, R., Nature, 198, 395 (1963).
5. Silvestroni, E., Bianco, I., and Brancati, C., Prog. Med., 17, 14 (1961).