1. Underwood, E. J., Trace Elements in Human and Animal Nutrition (Academic Press, New York, 1956).
2. Cox, W. M., jun., and Mueller, A. J., J. Nutrition, 13, 249 (1937).
3. Hodgkin, E. P., and Sheard, K. (edit.), J. Roy. Soc. West Austral., 42, Pt. 3, 65 (1959).
4. Josephs, H. W., Medicine, 15, 307 (1936).
5. Garcia, J. F., Amer. J. Physiol., 190, 19 (1957).