Linear Cryptanalysis and Modified DES with Embedded Parity Check in the S-boxes. - Yuri L. Borissov; Peter G. Boyvalenkov; Robert Tsenkov (BalkanCryptSec, 2015)

Two-Round Iterative Characteristics for Linear Cryptanalysis of Modified DES with Embedded Parity Checks. - Robert Tsenkov; Yuri L. Borissov (Electron. Notes Discret. Math., 2017)

On a Linear Cryptanalysis of a Family of Modified DES Ciphers with Even Weight S-boxes. - Yuri L. Borissov; Peter G. Boyvalenkov; Robert Tsenkov (IACR Cryptol. ePrint Arch., 2017)