Don discovers a treasure trove of digitized vintage radio books and magazines from https://swling.com/

 

Many thanks to SWLing Post contributor, Don (W7SSB), who writes:

I thought these links might be of interest to your readers:

https://www.qsl.net/va3iul/Files/Old_Radio_Frequency_Books.htm

https://www.qsl.net/va3iul/

Brilliant! Thanks for the tip, Don!

Of course, another deep treasure trove is the World Radio History website.