C.I. , Elekachi, et al. “ Developed Empirical Models for the Estimation of Global Solar Radiation With Sunshine Hours and Other Meteorological Data on a Horizontal Surface in Some Cities in North Central Geopolitical Zone in Nigeria ”. African Journal of Education,Science and Technology (AJEST), vol. 3, no. 4, May 2017, pp. Pg 87-96, http://ajest.org/index.php/ajest/article/view/191.