1. Bruen, A. A. and M. A. Forcinito. 2011. Cryptography, Information Theory, and Error-Correction: A Handbook for the 21st Century. Hoboken, NJ: John Wiley & Sons.
2. AUTOMATED CRYPTANALYSIS OF XOR PLAINTEXT STRINGS
3. Friedman, W. F. 1922. The Index of Coincidence and Its Applications in Cryptography. Riverbank Labs: Riverbank Publication.
4. On the security of multiple encryption
5. The 1944 Bletchley Park Cryptographic Dictionary https://www.codesandciphers.org.uk/documents/cryptdict/