Ronny, Ronny, Muhammad Ikbal Arif, and Hari Basuki Notobroto. “Water Pollution Index: Measurement of Shallow Well Water Quality in Urban Areas”. International Journal of Environment, Engineering and Education 1, no. 3 (December 19, 2019): 75–81. Accessed May 1, 2026. https://ijeedu.com/index.php/ijeedu/article/view/19.