William F. Friedman NSA Archive - Memoranda, Electronic Code Machine (ECM) Hebern (Including Negative Images of the Machine), 1924 - 4in1

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Files W.F.F. Archive Patent and Equipment Records Memoranda, Electronic Code Machine (ECM) Hebern (Including Negative Images of the Machine), 1924

Memorandum on Hebern Electric Code Machine

Document A273766

Negatives of Early Development Models ECM March 1 & 2

Document A4161641

Record of Inventions Photo Notes Kept by Non Seiler

Document A273768

Study of A Cipher Machine Being Considered for Use In the Naval Service

Document A273765