Nagy, P. T., I. Gonda, P. Dremák, and I. J. Holb. “Study on the Micronutrient Content of Soil and Leaf of an Organic Apple Orchard in Eastern Hungary”. International Journal of Horticultural Science 12, no. 3 (June 20, 2006): 7–11. Accessed May 11, 2021. https://ojs.lib.unideb.hu/IJHS/article/view/650.