T. B. Prasetyo, A. Maulana, M. Harianti, A. L. Lita, and Herviyanti, “Modification of Surface Charges on Ex-Gold Mining Soil Ameliorated with Activation of Sub-Bituminous Coal - NaOH”, Int. J. Adv. Sci. Eng. Inf. Technol., vol. 13, no. 5, pp. 1772–1780, Oct. 2023.