Akpenpuun, T. D., K. A. Adeniran, B. A. Akinyemi, and O. O. Ologun. “Development and Performance Evaluation of a Poultry Waste Management Technique Using Gravity Sand Filter ”. ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT, Vol. 13, no. 4, Aug. 2017, pp. 502-1, https://www.azojete.com.ng/index.php/azojete/article/view/720.