December 2020 was a good month for Cycle 25 sunspots - a bit lower than November, but we’ll take it! It’s still too early to make a guess as to what Cycle 25 might do.
ARRL DX CW 2012 - Which 10M Path
Is the ionosphere really lower
Grand Solar Minima
Butterfly Diagrams and Solar Minimum
A Look at All Twenty Three Solar Cycles
The Robust Equatorial Ionosphere