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\bibitem{AH88}
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\newblock {KRYPTON}: A functional approach to knowledge representation.
\newblock {\em IEEE Computer}, 16(11), 1983.

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\newblock An overview of the {KL-ONE} knowledge representation system.
\newblock {\em Cognitive Science}, 9(2), 1985.

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\newblock Semantic database modeling: Survey, applications and research issues.
\newblock {\em ACM Computing Surveys}, 19(3), September 1987.

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