Riverbank Publications No. 20 Several Machine-Ciphers and Methods for Their Solution
Riverbank, Geneva Ill. Riverbank Laboratories Department of Ciphers 1918. First Edition. [2], [1]-58, [28] pages 28.5 cm. Provided in the originally issued Riverbank Laboratories button and string flapped manila envelope with limitation number on outside. Individually numbered limitation of 200 copies (so stated on copyright page). Stiff tan publisher's wraps..... More