1. Abbot, C.G., Fowle, F.E., Aldrich, L.S.:1932,Ann.Smithson.Inst.Astrop. Obs. 5
2. Anon., Standard Specifications for Solar Constant and Air Mass Zero Solar Spectral Irradiance, ASTM Standard, E490-73a, 1974,Annual Book of ASTM Standards, part 41, Philadelphia, PA
3. Arvesen, I.C., Griffing, R.N. and Pearson, B.D.: 1969,Appl.Opt. 8, p.2215
4. Burlov-Vasiljev, K.A., Gurtovenko, E.A., Matvejev, Yu.B.:1992, Ed.Donnelly R.F.,Proceedings of the Workshop on Solar Cycle 22, 49
5. Hardrop, J.: 1980,Astron.Astrophys. 88, 334;