B. C. Sia, A. A. Fernandez, S. C. Chong, M. Falahat, and B. K. Sia, “A Case Study on Ranhill Water Services and Syarikat Air Negeri Sembilan in Combating the Non-Revenue Water Problem in Johor and Negeri Sembilan”, jgd, vol. 17, no. 1, pp. 1–17, Jan. 2021, doi: 10.32890/jgd2021.17.1.1.