Sipos, Marianna. 2008. “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):85-92. https://doi.org/10.34101/actaagrar/30/2996.