Zunita, M., and R. D. Rhamadhani. “A Kinetic Study of Manganese Leaching from Low-Grade Psilomelane Ore by Acetic-Tannic Acid Lixiviant”. ASEAN Journal of Chemical Engineering, Vol. 21, no. 2, Dec. 2021, pp. 249-71, https://journal.ugm.ac.id/v3/AJChE/article/view/9197.