1. Acton, L. W., Kreplin, R. W., Chubb, T. A., and Meekins, J. F.: 1963, J. Geophys. Res. 68, 3335.
2. Antalov�, A.: 1987, Contr. Astron. Obs. Skalnate Pleso 16, 79.
3. Antalov�, A.: 1988, Contr. Astron. Obs. Skalnate Pleso 17, 301.
4. Bevington, P. R.: 1969, Data Reduction and Error Analysis for the Physical Sciences, McGraw-Hill, New York.
5. Bouwer, S. D., Donnelly, R. F., Falcon, J., Quintana, A., and Caldwell, G.: 1982, NOAA Technical Memorandum ERL SEL-62, NOAA, Boulder, Colorado.