Jijingi, H. E., A. M. Ezekiel, and O. K. Duru. “Comparative Study of River Benue and River Asa Sand in North Central Nigeria As Filter Media”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 22, no. 1, July 2016, pp. 243-80, https://asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/1792.