1. S. K. Vsekhvyatskii, G. M. Nikol’skii, V. I. Ivanchuk, et al., Solnechnaya korona i korpuskulyarnoe izluchenie v mezhplanetnom prostranstve (Corona and Corpuscular Radiation in Interplanetary Space) (KU, Kiev, 1965) [in Russian].
2. G. Newkirk, Ann. Rev. Astron. Astrophys. 5, 213 (1967).
3. R. A. Howard, M. A. Koomen, D. J. Michels, et al., Synoptic Observations of the Solar Corona during Carrington Rotations 1580–1596, Report UAG-48, World Data Center for Solar—Terrestrial Physics (July 1975).
4. J. D. Bohlin, Sol. Phys. 12, 240 (1970).
5. L. Svalgaard, J. M. Wilcox, and T. L. Duvall, Sol. Phys. 37, 157 (1974).