Zahrim, A. Y., A. R. Rakmi, and M. S. Kalil. “Sludge Composting: A Case Study on Palm Oil Mill Sludge (POms)”. ASEAN Journal of Chemical Engineering, Vol. 7, no. 2, Dec. 2007, pp. 102-7, https://dev.journal.ugm.ac.id/v3/AJChE/article/view/7682.