Mukhlis, T., I. Amri, and Z. Helwani. “Upgrading Karakteristik Biopelet Tandan Kosong Sawit Dengan Penambahan Oil Sludge Sebagai Co-Firing”. Journal of Bioprocess, Chemical and Environmental Engineering Science, Vol. 2, no. 1, Mar. 2021, pp. 45-55, doi:10.31258/jbchees.2.1.1-11.