(Available online)* Singh, Simon (1999) "" New York: Doubleday ISBN 0-385-49531-5* An Overview of Public Key Cryptography Martin E. Hellman, IEEE Communications Magazine, May 2002, pp:42–49.
(Available online)* Singh, Simon (1999) The Code Book: the evolution of secrecy from Mary Queen of Scots to quantum cryptography New York: Doubleday ISBN 0-385-49531-5* An Overview of Public Key Cryptography Martin E. Hellman, IEEE Communications Magazine, May 2002, pp: 42—49.