NSA Museum Library has provided "Hagelin M-209 Cryptanalysis from Ciphertext Alone,"
Reeds, Ritchie, Morris, 1978.

https://cryptome.org/2015/12/ReedsTheHagelinCipherBellLabs1978.pdf

NSA would not release it under FOIA, claiming it was a private paper.

Back story:

http://bell-labs.com/usr/dmr/www/crypt.html