Eltawab, R., M. . Ayoub, A. . . El-Morsy, and H. . Afify. “Evaluating Performance of Different Filter Media Stratification for Tertiary Treatment of Wastewater”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 61, no. 1, Dec. 2019, pp. 289-03, https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/5356.