1. Bussler, W. (1983): Mangelerscheinungen an höheren Pflanzen. Literatur 1979-1982. Z. f. Pflanzenkrank-heiten und Pflanzenschutz 90, 415–447.
2. El-Foul, M.M. (1983): Micronutrients in arid and semi-arid areas: Levels in soils and plants and the need for fertilizers with reference to Egypt. Proc. 17th Colloq. Int. Potash Inst. Bern, 1963–173.
3. El-Fouly, M.M.; Fawzi, A.F.A.; Firgani, A.H. AND El-Baz, F.K. (1984): Micronutrient status in selected areas and crops in Egypt in relation to NPK. Comm. in Soil Science Plant Anal. 15, 1175–1189 (1984).
4. El-Fouly, M.M. (1984): Soil testing and leaf analysis for optimizing fertilizers1 use in field crops in Egypt. Proc. VI Inter. Colloq. for the optimization of plant nutrition, vol. 1, 173–180.
5. El-Fouly, M.M. (1985): Nutritional deficiencies and use of soil testing and leaf analysis as basis for mineral fertilization for oranges in Egypt. Acta Horticulturae 158, 321–330.