Widyatmoko, Bondan. “The Implementation of Indonesian Sustainable Palm Oil Certification (ISPO): Opportunity for Inclusion of Palm Oil Smallholder in Riau Province”. Masyarakat Indonesia 45, no. 2 (December 30, 2019): 219–228. Accessed December 6, 2025. https://ejournal.brin.go.id/jmi/article/view/8366.