Talk:Hollow Nickel Case

A more detailed description of the Hollow Nickel Case, including a "second act" between the discovery of the coin and the trial as well as a detailed description of the method required to decrypt the code (involving a substitution and two transpositions) is contained in "Codebreakers" by David Kahn (published about 1950) and available in some libraries. — Preceding unsigned comment added by Lucky Vassall (talk • contribs) 18:45, 16 June 2019 (UTC)