1. Allen, C. W.: 1955, Astrophysical Quantities, The Athlone Press, Univ. of London, London, p. 143.
2. Hildner, E.: 1977, in M. A. Shea, D. F. Smart and S. T. Wu (eds.), Study of Travelling Interplanetary Phenomena, D. Reidel Publ. Co., Dordrecht, Holland, p. 6.
3. Report UAG-48;R. A. Howard,1975
4. Koomen, M. J., Detwiler, C. R., Brueckner, G. E., Cooper, H. W., and Tousey, R.: 1975, Appl. Opt.
14, 743.
5. Koomen, M. J., Sheeley Jr., N. R. Michels, D. J., and Howard, R. A.: 1980, Sky Telesc.
60, 102.