Nagy, P. T., Z. Szabó, J. Nyéki, I. Gonda, and I. J. Holb. “Organic Versus Integrated Apple Growing: I. Differences in Soil and Leaf Parameters”. International Journal of Horticultural Science 15, no. 4 (September 2, 2009): 57-60. Accessed September 19, 2020. https://ojs.lib.unideb.hu/IJHS/article/view/841.