TY  - RPRT
TI  - Changes of lower ionosphere electron concentrations with solar activity.
AU  - Mechtly, E. A.
AU  - Bowhill, S. A.
AU  - Smith, L. G.
PY  - 1972
UR  - https://ntrs.nasa.gov/citations/19730027227
ID  - 19730027227
ER  -