1. Druckrey, H., Preussmann, R., Ivankovic, S., Schmidt, L. H., Mennel, H. D., and Stahl, K. W., Z. Krebsforsch., 66, 280–290 (1964).
2. Ito, N., Hisa, Y., Tamai, A., Okajima, E., and Kitamura, H., Gann, 60, 401–410 (1969).
3. Bertram, J. S., and Craig, A. W., Europ. J. Cancer, 8, 587–594 (1972).
4. Okada, M., and Suzuki, E., Gann, 63, 391–392 (1972).
5. Hashimoto, Y., Suzuki, E., and Okada, M., Gann, 63, 637–638 (1972).