Propagation
Propagation websites:
http://www.astrosurf.com/luxorion/qsl-propa4.htm
https://www.hamuniverse.com/hfbands.html
https://www.rcarc.org/presentations/HFPropagation.pdf
https://www.ng3k.com/misc/n4kgprop.html
https://www.qsl.net/ad4dx/pdf/radio02.pdf
http://www.nadxc.org/wp-content/uploads/2020/05/The-Magic-of-SW-Morning-Propagation.pdf
https://www.n1fd.org/2017/12/03/propagation-prediction-websites/
Digital modes propagation:
http://spotty.modern-industry.com
https://www.reversebeacon.net/