James P. Davis, Ronald D. Bonnell. Modeling Semantics with Concept Abstraction in the EARL Data Model. In Frederick H. Lochovsky, editor, Entity-Relationship Approach to Database Design and Querying, Proceedings of the Eight International Conference on Enity-Relationship Approach, Toronto, Canada, 18-20 October, 1989. pages 95-110, North-Holland, 1989. [doi]