Siallagan, Irwan, Sudradjat , and Hariyadi ,. “Optimasi Dosis Pupuk Organik Dan NPK Majemuk Pada Tanaman Kelapa Sawit Belum Menghasilkan”. Jurnal Agronomi Indonesia (Indonesian Journal of Agronomy) 42, no. 2 (January 2, 2015). Accessed August 23, 2026. https://journal.ipb.ac.id/jurnalagronomi/article/view/8824.