1. Nettleship, A., and Henshaw, P. S., J. Nat. Cancer. Inst, 4, 309 (1943)
2. Jaffe, W. G., Cancer Res., 7, 107 (1947).
3. Tannenbaum, A., and Silverstone, H., Cancer Res., 18, 1225 (1958).
4. Cowen, P. N., (unpublished).
5. Cowen, P. N., Brit. J. Cancer, 4, 245 (1950).