Files W.F.F. Archive Patent and Equipment Records Patent File, SISDE-6 Authentograph System, 1935-1937
Friedman Patent Application, Ser. No. 28,500 Message Authenticating System
Friedman Patent Application-Improvement: Message Authenticating System
General Description-the Friedman Authentograph
Patent Application for A Cryptographic Machine-Friedman
Patent Application-Friedman Cipher Device
Patents Originated by Government Employees