1. In 6-Mercaptopurine, edit. by Miner, R. W., and Rhoads, C. P., Ann. N.Y. Acad. Sci., 60, 183 (1954).
2. Brockman, R. W., Adv. in Cancer Res., 7, 129 (1963).
3. Paterson, A. R. P., and Sutherland, A., Can. J. Biochem., 42, 1415 (1964).
4. Utter, M. F., in The Enzymes, second ed., edit. by Boyer, P. D., Lardy, H., and Myrbäck, K., 2, 75 (Academic Press, Inc., New York, 1960).
5. Montgomery, J. A., Dixon, G. J., Dulmadge, E. A., Thomas, H. J., Brockman, R. W., and Skipper, H. E., Nature, 199, 769 (1963).