A.A.S. Tigue, J.M.S. Catapang, C.S.N. Chang, K.A. Collo, W. Kurniawan, H. Hinode, A.H. Orbecido, M.A.B. Promentilla, Synthesis of Pervious Geopolymer from Coal Fly Ash and Bagasse Fly Ash for Copper Removal, Chemical Engineering Transactions. 88 (2021) 817-822. doi:10.3303/CET2188136.