Zainol, Noor Ainee, et al. “Turbidity Removal from Kaolin Synthetic Wastewater via Coagulation Process Using Sludge from Water Treatment Plant”. International Journal of Integrated Engineering, vol. 14, no. 9, Dec. 2022, pp. 222-31, https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/12831.