German translation of Friedman's 'The Index of Coincidence'

A German translation of William F. Friedman's The Index of Coincidence and its Applications in Cryptanalysis, made by Austrian codebreaker Andreas Figl in 1938. Titled Die Anzeichen Der Zusammentreffen und Ihre Anwendung In Der Entraetselungskunst, it was based on a French translation of Friedman's text.

According to correspondence between Figl and Friedman held by the United States National Security Agency (NSA), this translation was made by Figl upon the request of a "friend." This is evident in the handwritten inscription in the manuscript, which states: "Meinem lieben Berufenen unseres geheimen Dienstes zur Förderung seiner Studien gewidmet. Wien, am 8. März 1938" (Dedicated to my dear recruit into our Secret Service, to expand his studies. Vienna, 8 March 1938). The manuscript is signed twice by Figl.

A copy was later given to Friedman in the 1950s and is now part of the Friedman Collection at the George C. Marshall Foundation. It is the only other known copy of this text.