K. Nguyen, Q. N. V. My, A. P. T. Kim, P. T. Tran, D. Huynh, and O. Le, “Coal fly ash-slag and slag-based geopolymer as an absorbent for the removal of methylene blue in wastewater”, VNUHCM Journal of Science and Technology Development, vol. 25, no. 1, pp. 2215-2223, Mar. 2022.