1. S. P. Langley,Acad. Sci. C. R.,95, 482 (1882).
2. S. P. Langley and C. G. Abbot,Ann. Smithson Inst. Astrophys. Obs., Vol. 1 (1990).
3. E. A. Makarova and A. V. Kharitonov,Energy Distribution in the Solar Spectrum and the Solar Constant [in Russian], Nauka, Moscow (1972).
4. The Solar Output and its Variation (O. R. White, ed.), Colorado Associated University Press, Boulder (1977).
5. P. N. Antroshchenko, A. S. Gadun, S. I. Gopasyuk, et al.,Variations in Global Solar Characteristics [in Russian], Naukova Dumka, Kiev (1992).