1. Gaush, C. R., Hard, W. L. & Smith, T. F. Proc. Soc. exp. Biol. Med. 122, 931–935 (1966).
2. Arcos, J. C. & Argus, M. F. Chemical Induction of Cancer 2A (Academic, New York, 1974).
3. Survey of Compounds which have been Tested for Carcinogenic Activity, USPHS Publication No. 149 (US Government Printing Office, Washington DC, 1972–73).
4. Hecht, S. S., Loy, M. & Hoffmann, D. Carcinogenesis 1, 325–340 (Raven, New York, 1976).
5. Wong, J. J. & Hsieh, D. P. H. Proc. natn. Acad. Sci. U.S.A. 73, 2241–2244 (1976).