Umaru, A. B., S. Lukman, I. A. Oke, and B. G. Umara. “A New Formula for Groundwater Recharge Estimation in Yola, Nigeria”. ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY AND ENVIRONMENT, Vol. 15, no. 4, Dec. 2019, pp. 847-58, https://www.azojete.com.ng/index.php/azojete/article/view/139.