1. F. Bohlmann, J. Ebert, and R. Süttenbach. An OMT Metamodel. Projektbericht 1/96, UniversitÄt Koblenz-Landau, Institut für Softwaretechnik, Koblenz, 1996.
2. J. B. Behm and T. J. Teorey. Relative Constraints in ER Data Models. R. A. Elmasri, V. Kouramajian, B. Thalheim (Eds.): Entity-¯Relationship Approach — ER '93, 12th International Conference on the Entity-Relationship Approach, Arlington, Texas, USA, December 15–17, 1993, pages 46–59, 1994.
3. M. Carstensen, J. Ebert, and A. Winter. Entity-Relationship-Diagramme und Graphenklassen. to appear as Fachbericht Informatik, 1996, Institut für Softwaretechnik, UniversitÄt Koblenz-Landau, 1996.
4. P. P.-X. Chen. The Entity-Relationship Model — Toward a Unified View of Data. ACM Transactions on Database Systems, 1(1):9–36, March 1976.
5. B. Courcelle. Graph structure definition using monadic second-order languages. In: Proceedings of the Workshop on Finite Models and Descriptive Complexity, Princeton, New Jersey, January 14–17, 1996, to appear in: AMS-DIMACS Series in Discrete Mathematics and Theoretical Computer Science, 1996.