1. Cook, J. W., Hewett, C. L., and Hieger, I., J. Chem, Soc., 395 (1933).
2. Winterstein, A., Festschrift Emil Bareli, Basel (1936), quoted by Cook, J. W., and Kennaway, E. L., Amer. J. Cancer, 33, 50 (1938).
3. Berenblum, I., and Schoental, R., Brit. J. Exp. Path., 24, 232 (1943).