1. Chapman, H., and Pratt, P. F., Methods of Analysis for Soils, Plants and Waters. Univ. California Div. Agr. Sci. (1961).
2. Elgabaly, M. M., Plant and Soil16, 157–164 (1962).
3. Fawzy, H.et al., Plant Physiol.29, 234–237 (1954).
4. Hoagland, D. R., and Davis, A. R., Protoplasma6 (1926).
5. Hoagland, D. R., and Broyer, T. C., Am. J. Botany27, 173–185 (1940).