This is the article by Ingesson and Andersson. Clandestine communications in cyber-denied Environments: Numbers stations and radio in the 21st century https

This is the article by Ingesson and Andersson. Clandestine communications in cyber-denied Environments: Numbers stations and radio in the 21st century https://www.tandfonline.com/doi/epdf/10.1080/18335330.2023.2209578?needAccess=true https://www.tandfonline.com/doi/epdf/10.1080/18335330.2023.2...