1. Smith, J. E. & Goodman, D. S. Fedn Proc. 38, 2504–2509 (1979).
2. Goodman, D. S. Fedn Proc. 38, 2501–2503 (1979).
3. De Luca, L. M. et al. Report of the International Vitamin A Consultative Group (Nutrition Foundation, New York, 1978).
4. Olson, J. A. & Hayaishi, O. Proc. natn. Acad. Sci. U.S.A. 54, 1364–1370 (1965).
5. Nieman, C. & Obbink, H. J. K. Vita. Horm. 12, 69–99 (1954).