1. A. B. Severnyi, Izv. Krym. Astrofiz. Obs.,36, 97 (1966).
2. S. I. Gopasyuk and T. T. Tsap, Soln. Dannye, No. 4 (1972).
3. A. B. Severnyi (Severnij) and R. Wilcox, Astron. J.,146, 211 (1973).
4. W. Tandberg-Hanssen, Sol. Phys.,34, 210 (1975).
5. G. Ya. Smolkov and V. S. Bashkirtsev, Proc. Seventh Reg. Consult.