IEEE
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... Internet Environments: A Hierarchical Key Management Scheme for End-to-End Encryption", IEEE Transactions on Communications, Vol. 37, No. 10, Pg. 1014, 1 October 1989. ...
... W. Lu and M. Sundareshan, "A Model for Multilevel Security in Computer Networks", IEEE Transactions on Software Engineering, Vol. 16, No. 6, Page 647, 1 June 1990. ...