G. Z., Ugwu, and Alasi T. K. “Aeromagnetic Survey for Determining Depth to Magnetic Source of Abakaliki and Ugep Areas of the Lower Benue Trough, Nigeria”. Engineering And Technology Journal, vol. 1, no. 01, Sept. 2016, pp. 18-31, http://everant.org/index.php/etj/article/view/173.