Husin, Haslina, et al. “Optimization of Ammonia Removal from Landfill Leachate by Aeration Using Response Surface Methodology (RSM)”. International Journal of Integrated Engineering, vol. 16, no. 4, Aug. 2024, pp. 179-87, https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/16206.