Zable, M. A. H., et al. “Investigation on Dielectric Properties of Sludge Waste from Water Treatment Using Microwave Non-Destructive Testing (MNDT)”. International Journal of Integrated Engineering, vol. 15, no. 3, Aug. 2023, pp. 163-9, https://penerbit.uthm.edu.my/ojs/index.php/ijie/article/view/12886.