1. Solar Engineering of Thermal Processes;Duffie,1980
2. An Introduction to Solar Radiation;Iqbal,1983
3. Calculation of monthly average insolation on tilted surfaces;Klein;Sol. Energy,1977
4. P. C. Jain, Table for monthly average daily extra-terrestrial irradiation on horizontal surface and the maximum possible sunshine duration, ICTP, Trieste, Internal Report IC/84/7.
5. Fourier series representation of the position of the sun;Spencer;Search,1971