* Jeffrey Overbey, William Traves, and Jerzy Wojdylo, On the Keyspace of the Hill Cipher, "Cryptologia", Vol.29, No.1, January 2005, pp59–72.
* Jeffrey Overbey, William Traves, and Jerzy Wojdylo, On the Keyspace of the Hill Cipher, "Cryptologia", 29(1), January 2005, pp59–72.