TY  - RPRT
TI  - Solar flare activity - Evidence for large-scale changes in the past
AU  - Zook, H. A.
AU  - Hartung, J. B.
AU  - Storzer, D.
PY  - 1977
UR  - https://ntrs.nasa.gov/citations/19770063695
ID  - 19770063695
ER  -