Agustira, M. A., D. Siahaan, and H. A. Hasibuan. “ECONOMIC VALUE OF OIL PALM SAP AS POTENTIALLY FINANCING FOR OIL PALM SMALLHOLDERS REPLANTING”. Jurnal Penelitian Kelapa Sawit, Vol. 27, no. 2, Aug. 2019, pp. 115-26, doi:10.22302/iopri.jur.jpks.v27i2.62.