Akyol, Ç., Özbayram, E.G., İnce, O., Kleinsteuber, S., İnce, B., 'Anaerobic Co-digestion of Cow Manure and Barley: Effect of Cow Manure to Barley Ratio on Methane Production and Digestion Stability', Environmental Progress & Sustainable Energy, 35, 2, 589-595, 2016.