1. Arnon, D. I., Amer. J. Bot., 25, 322 (1938); Science, 92, 264 (1940).
2. Grahame, D. C., and Seaborg, G. T., J. Amer. Chem. Soc., 60, 2524 (1938). Sandell, E. B., “Colorimetric Determination of Traces of Metals” (Interscience, N.Y., 1949).
3. Arnon, D. I., in “Mineral Nutrition of Plants”, edit. by Truog, E. (Univ. Wis. Press, Madison, Wis., 1952).
4. Arnon, D. I., and Stout, P. R., Plant Physiol., 14, 599 (1939).
5. Bertrand, D., Bull. Soc. Chem. Biol., 23, 390 (1941); C.R. Acad. Sci., Paris, 213, 254 (1941).