Shahputra, M. Afif. “ANALISIS FINANSIAL BIOGAS LIMBAH CAIR KELAPA SAWIT SEBAGAI ENERGI TERBARUKAN DI PKS RAMBUTAN PTPN III (FINANCIAL ANALYSIS OF PALM OIL BIOGASS FROM MILL EFFLUENT OF CRUDE PALM OIL FACTORY AS A RENEWABLE ENERGY IN PKS RAMBUTAN PTPN III)”. Inovasi, vol. 14, no. 2, Oct. 2017, pp. 180-9, http://jurnal.bappelitbang.sumutprov.go.id/index.php/inovasi/article/view/104.