Mohd Arshad, Nur Ain Nazirah, and R. Hamdan. “Study of Steel Slag Filter Unit As a Secondary Treatment System for Removing Total Phosphorus from Textile Industry Wastewater”. International Journal of Integrated Engineering, vol. 13, no. 3, June 2021, pp. 192-9, https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/8930.