1. Creech, H. J., Hauschka, T. S., Hankwitz, Jr., R. F., Littleton, B. J., and Andre, J., Cancer Res., Supp. No. 3, 47 (1955).
2. Furst, A., Cutting, W. C., and Gross, H. S., Cancer Res., 15, 294 (1955).
3. Riley, J. F., Cancer Res., 8, 783 (1948).
4. Vivian, D. L., J. Org. Chem., 21, 1034 (1956).