Szendrei, János, and Gábor Grasseli. “Study of The Amount of Produced Animal Manure and Biogas Potential in a 5, 20 and 40 Km Zone Around Debrecen”. Acta Agraria Debreceniensis, no. 22 (May 23, 2006): 64–68. Accessed July 1, 2022. https://ojs.lib.unideb.hu/actaagrar/article/view/3193.