Mirnawati, Yose Rizal, Yetti Marlida, and I. Putu Kompiang. “The Role of Humic Acid in Palm Kernel Cake Fermented by Aspergillus Niger for Poultry Ration”. Pakistan Journal of Nutrition 9, no. 2 (January 15, 2010): 182–185. Accessed September 1, 2025. https://pjnonline.org/pjn/article/view/1148.