J.U. Ugwuanyi, E.I Echi, J.T Azoom,. “Comparison of Empirical Models in the Estimation of Global Solar Radiation over Nigeria”. International Journal of Engineering and Computer Science 4, no. 10 (October 28, 2015). Accessed April 30, 2024. http://ijecs.in/index.php/ijecs/article/view/2980.