Sipos, Marianna. “The Effect of Nickel-Contamination, Nitrogen-Supply and Liming on the Chemical Composition of Perennial Ryegrass (Lolium Perenne L.)”. Acta Agraria Debreceniensis, no. 30 (October 10, 2008): 85–92. Accessed October 19, 2021. https://ojs.lib.unideb.hu/actaagrar/article/view/2996.