> Fernandez, who more than two decades ago published a four-CD audio compendium of hundreds of recordings from around the world called the Conet Project. It's considered the Bible for numbers-station enthusiasts.

The Conet Project is an interesting listen -- very analogue, Cold War-ish, and a bit sinister. Seems to be available on the Internet Archive at https://archive.org/details/The-Conet-Project