Daud, Zawawi, Shahril Effendi A Rahman, Halizah Awang, Mahmoud Hijab Abubakar, Mohd Baharudin Ridzuan, and Husnul Azan Tajarudin. “Utilization of Waste Paper Sludge As an Alternative Adsorbent for the Adsorption of Ammonia Nitrogen and COD in Stabilized Landfill Leachate”. International Journal of Integrated Engineering 10, no. 9 (January 1, 2019). Accessed May 29, 2020. https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/3012.