1. Christos Military and Intelligence Corner. 2017 February 1. The compromise of the Croat Enigma K cipher by the German Army’s codebreakers. Accessed July 29 2024. https://chris-intel-corner.blogspot.com/2017/02/the-compromise-of-croat-enigma-k-cipher.html
2. Frode Weierud’s CryptoCellar. 2016. The Enigma Collection.” Accessed July 29 2024. https://cryptocellar.org/enigma/
3. TICOM I-92. 1945 September 11. Final interrogation of Wachmeister Otto Buggisch (OKH/IN and OKW/CHI). Accessed 29 July 2024. https://www.cryptomuseum.com/ticom/files/i92.pdf
4. German mathematicians and cryptology in WWII