Mézes, Lili, Tibor Bíró, János Tamás, and Mihály Petis. “The Examination of Poultry Feather Digestility for Biogas Production”. Acta Agraria Debreceniensis0, no. 26 (July 16, 2007): 113-118. Accessed September 28, 2020. https://ojs.lib.unideb.hu/actaagrar/article/view/3064.