Hassim, N. A. A., K. C. Hui, D. Floresyona, N. A. Kamal, and N. S. Sambudi. “Effect of PH on Adsorption of Cu2+ by Using Composite of Polyvinyl Alcohol (PVA)/Kaolin”. ASEAN Journal of Chemical Engineering, Vol. 22, no. 1, June 2022, pp. 93-104, https://dev.journal.ugm.ac.id/v3/AJChE/article/view/9230.