Zahrim, A. Y., A. R. Rakmi, and M. S. Kalil. 2007. “Sludge Composting: A Case Study on Palm Oil Mill Sludge (POms)”. ASEAN Journal of Chemical Engineering 7 (2), 102-7. https://dev.journal.ugm.ac.id/v3/AJChE/article/view/7682.