1. Adani, F. and Genevini, P. and Zaccheo, P. and Zocchi, G. (1998) The effect of commercial humic acid on tomato plant growth and mineral nutrition Journal of Plant Nutrition, 21, pp. 561 - 575.
2. Alloway, B.(2004) Zinc in Soils and Crop Nutrition. Brussels : IZA Publications and International Zinc Association Communications.
3. Arnesen, A. and Singh, B. (1998) Plant uptake and DTPA‐extractability of Cd, Cu, Ni and Zn in a Norwegian alum shale soil as affected by previous addition of dairy and pig manures and peat Canadian Journal of Soil Science, 78, pp. 531 - 539.
4. Bar‐Tal, A. and Bar‐Yosef, B. and Chen, Y. (1988) Effects of fulvic acid and pH on zinc sorption on montmorillonite Soil Science, 146, pp. 367 - 373.
5. Cakmak, I. and Yilmaz, A. and Ekiz, H. and Torun, B. and Erenoglu, B. and Braun, H. (1996) Zinc deficiency as a critical nutritional problem in wheat production in Central Anatolia Plant and Soil, 180, pp. 165 - 172.