Khairul, Khairul, Ajidirman, and Sunarti. 2022. “The Physico Chemical Properties of Coal Mined Soil and Soybean Yield under Ameliorant Residue of In Situ Bituminous Coal and Its Coal Impurities”. Akta Agrosia 25 (2):52-61. https://ejournal.unib.ac.id/Agrosia/article/view/25581.