1. D. Basu, Nature,212, No. 5064, 804 (1966).
2. Tanaka Haruo, Proc. Res. Inst. Atmos., Nagoya Univ.,11, 41 (1964).
3. Y. Leblanc and A. M. Le Squeren, Astron. and Astrophys.,1, No. 2, 239 (1969).
4. Solnechnye Dannye (Solar Data) (1961?1966).
5. Quarterly Bulletin on Solar Activity (1961?1966).