“Study of Soil Chemical Properties on Palm Oil Productivity in PT. Gemilang Sejahtera Abadi in East Kalimantan”. JOURNAL OF TROPICAL SOILS 29, no. 3 (December 27, 2023): 127–133. Accessed October 31, 2025. https://journal.unila.ac.id/index.php/tropicalsoil/article/view/572.