Umam, R., S. Suharno, and R. Junaidi. “Geochemical Evidence from Major and Trace Elements in Geothermal Waters of Empat Lawang, Southern Sumatra: Clues to Mineralization and Hydrothermal Sources”. Leuser Journal of Environmental Studies, vol. 3, no. 2, Oct. 2025, pp. 87-98, doi:10.60084/ljes.v3i2.343.