Canbolat O, Kamalak A, Ozkose E, Ozkan C O, Sahin M and Karabay P 2005: Effect of polyethylene glycol on in vitro gas production, metabolizable energy and organic matter digestibility of Quercus cerris leaves. Livestock Research for Rural Development. Volume 17, Article #42. Retrieved
, from http://www.lrrd.org/lrrd17/4/canb17042.htm