1. Solar Radiation;Robinson,1966
2. Direct solar radiation on various slopes from 0 to 60 degrees North latitude;Buffo,1972
3. Solar and terrestrial radiation;Angstrom;Quart. J. Roy. Met. So.,1924
4. Lehrbuch der Meteorologie;Hann,1901
5. Intensitat und Spektralverteilung der Globalstrahlung bei klaren Himmel;Albrecht;Arch. Met., Geophys., Bioklim.,1951