Fernando Sitorus, A. ., H. . Bagus Pulunggono, S. . Anwar, and B. . Nugroho. “Diagnosis of Macronutrients in Oil Palm (Elaeis Guineensis Jacq.) Using DOP and DRIS Methods”. Jurnal Penelitian Kelapa Sawit, vol. 32, no. 2, Aug. 2024, pp. 83-94, doi:10.22302/iopri.jur.jpks.v32i2.245.