1. W. Diffie, M. Hellman, New directions in cryptography, IEEE Transactions on Information Theory, November 1976, p. 648.
2. L.M. Kohnfelder, Towards a practical public-key cryptosystem, May 1978, p. 15.
3. ITU-T Recommendation X.509, first published in 1988 but updated frequently, e.g., ISO/IEC 9594-8:1994, Information Technology – Open Systems Interconnections – The Directory: Authentication Framework.
4. S. Kent, J. Linn, Privacy Enhancement for Internet Electronic Mail: Part II – Certificate-Based Key Management, RFC 1114, August 1989.
5. C.M. Ellison, Establishing identity without certification authorities, 6th USENIX Security Symp., July 1996, http://www.pobox.com/∼cme/usenix.html.