Just a bit of coffee table or radio room books if you are a user of KiwiSDR or RTL-SDR hardware.
KiwiSDR: 21st Century Radio for the People
https://tinyurl.com/kiwisdr01
Airband Radio on the RTLSDR
https://tinyurl.com/rtlsdr01
Those radio devices are incredible, as they make radio spectrum into something that can be processed and shared like the text on this website.