History of Amateur Radio/Radio
http://www.arrl.org/files/file/About%20ARRL/Ham_Radio_100_Years.pdf
https://w6sg.net/site/a-brief-history-of-amateur-radio/
https://www.electronics-notes.com/articles/history/amateur-ham-radio/history.php
http://www.astrosurf.com/luxorion/qsl-ham-history.htm
https://earlyradiohistory.us/sec012.htm
https://en.wikipedia.org/wiki/History_of_radio
https://www.britannica.com/topic/radio
https://transition.fcc.gov/omd/history/radio/documents/short_history.pdf