Shaikh, S. A., N. Gul, and L. Sultana. “Surveillance of Drinking Water of Karachi City: Microbiological Quality”. Biological Sciences - PJSIR, vol. 51, no. 5, Sept. 2008, pp. 272-5, https://v2.pjsir.org/index.php/biological-sciences/article/view/695.