1. Dennis K. Branstead, Jason Gait, and Stuart Katzke, “Report of the Workshop on Cryptography in Support of Computer Security,” National Bureau of Standads, September 21–22, 1976, NBSIR 77-1291, September 1977.
2. Dorothy E.R. Denning, “Cryptography and Data Security,” Addison-Wesley, Menlo Park, California, 1983.
3. Alan G. Konheim, “Cryptography, A Primer,” John Wiley, New York, 1981.
4. Lexar Corporation, “An Evaluation of the NBS Data Encryption Standard,” unpublished report, Lexar Corporation, 11611 San Vicente Blvd., Los Angeles, 1976.
5. National Bureau of Standards, “Encryption Algorithm for Computer Data Protection,” Federal Register, 40, March 17, 1975, pp. 12134–12139.