1. Akinyan, ST., Fomichcf, V.V., Chertok, I.M. and Kruger. A.: 1979. Phys. Solariterr. 11, 5
2. Gergely. T.E.: 1986, Solar Phys
104, 175
3. Gil, G., Mćndcz, A. and Rodríguez,. R.E.: 1994, Available upon request. Institute of Geophysics and Astronomy, Calle 221 No. 2905, La Coronela, Havana Cuba
4. Harrison, R.A.: 1986, Astron. Astrophys
162, 283
5. Harrison, R.A.: 1990, Solar Phys
126, 185