Darmayanti, L., Notodarmodjo, S. and Damanhuri, E. (2017) “Removal of Copper (II) Ions in Aqueous Solutions by Sorption onto Fly Ash”, Journal of Engineering and Technological Sciences, 49(4), pp. 546-559. doi: 10.5614/j.eng.technol.sci.2017.49.4.9.