1. H.J. Beker, J.M.K. Friend, P.W. Halliden; Simplifying key management in electronic fund transfer point of sale systems, Electronics Letters Vo1.19 No.12 (1983), 442–444.
2. H.J. Beker; Secure electronic funds transfer in a retail environment; Networks 84, Proceedings of the European Computer Communications Conference (1984), 263–270.
3. American National Standard; “Data Encryption Algorithm”, ANSI X3.92 (1981).
4. American National Standard; “Pin Management and Security”, ANSI X9.8 (1982).
5. American National Standard; “Financial Institution Message Authentication”, ANSI X9.9 (1982).