Ahmed, Imran, et al. “Analysis and Treatment of Tannery Waste Water by Using Combined Filtration and Coagulation Treatment Process: Treatment of Tannery Waste Water by Using Combined Filtration and Coagulation”. Proceedings of the Pakistan Academy of Sciences: B. Life and Environmental Sciences, vol. 53, no. 3, Sept. 2016, pp. 179–183, http://ppaspk.org/index.php/PPAS-B/article/view/327.