Al-Rawahi, N., Y. Zurigat, and N. Al-Azri. “Prediction of Hourly Solar Radiation on Horizontal and Inclined Surfaces for Muscat/Oman”. The Journal of Engineering Research [TJER], vol. 8, no. 2, Dec. 2011, pp. 19-31, doi:10.24200/tjer.vol8iss2pp19-31.