1. ASHRAE, 1972. Handbook of Fundamentals. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA.
2. ASTM, 2003. Standard Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37° Tilted Surface. Standard G173-03. American Society for Testing and Materials, West Conshohocken, PA. .
3. A numerical solar radiation model based on standard meteorological observations;Atwater;Solar Energy,1978
4. Estimation of hourly clear-sky solar radiation for P.D.R. Yemen;Aziz;Solar Wind Technology,1990
5. Verification of some very simple clear and cloudy sky models to evaluate global solar irradiance;Badescu;Solar Energy,1997