Berta-Szabó, Emese, György Zsigrai, Anita Szabó, and Jakab Loch. 2010. “Effects of Long-Term K Fertilization and Liming on the Extractable and Exchangeable K Contents of a Haplic Phaeosem Soil”. Acta Agraria Debreceniensis, no. I (October): 141-45. https://ojs.lib.unideb.hu/actaagrar/article/view/8392.