https://www.nsa.gov/news-features/declassified-documents/tec...
> Key to The Extraterrestrial Messages - Winter 1969 - Vol. XIV, No. 1
Additionally, that same link above also contains this from the Winter 1966 journal, "Communication with Extraterrestrial Intelligence":
https://www.nsa.gov/Portals/70/documents/news-features/decla...