1. Matthews-Roth, M.M.: Antitumor activity of betacarotene, canthaxanthin and phytene. Oncology 39:33–37, 1982.
2. Rettura, G., Stratford, F., Levenson, S.M., and Seifter, E.: Prophylactic and therapeutic actions of supplemental beta-carotene in mice inoculated with C3HBA adenocarcinoma cells: lack of action of supplemented ascorbic acid. J. Natl. Cancer Inst. 69:73–77, 1982.
3. Temple, N.J., and Basu, T.K. Protective effect of beta-carotene against colon tumors in mice. J. Natl. Cancer Inst. 78:1211–1214, 1987.
4. Shekelle, R.B., Lepper, N., Lui, S., et al.: Dietary vitamin A and risk of cancer in the Western Electric Study. Lancet 2:1185–1189, 1981.
5. Graham, S., Mettlin, C., Marshall, J., et al.: Dietary factors in the epidemiology of cancer in the larnyx. Am. J. Epid. 113:675–680, 1981.