1. K. Mengel, E. A. Kirkley,Principles of Plant Nutrition, International Potash Institute, Worb-laufen-Bern, 1978.
2. A. L�uchli, R. L. Bieleski (eds.),Inorganic Plant Nutrition, Vols. 15A/B, Encyclopedia of Plant Physiology, Springer, Berlin Heidelberg New York Tokyo, 1983.
3. A. Kabata-Pendias, H. Pendias (eds.),Trace Elements in Soil and Plants, CRC-Press, Boca Raton, 1985.
4. W. Pfannhauser,Essentielle Spurenelemente in der Nahrung, Springer, Berlin Heidelberg New York Tokyo, 1988.
5. E. Merian (ed.),Metals and Their Compounds in the Environment, VCH Verlag, Weinheim, 1991.