1. Angele, J., Boley, H., de Bruijn, J., Fensel, D., Hitzler, P., Kifer, M., Krummenacher, R., Lausen, H., Polleres, A., Studer, R.: Web Rule Language (WRL). World Wide Web Consortium, W3C Member Submission (September 2005), http://www.w3.org/Submission/WRL/
2. Brockmans, S., Haase, P.: A Metamodel and UML Profile for Rule-extended OWL DL Ontologies –A Complete Reference. Technical report, Universität Karlsruhe (March 2006), http://www.aifb.uni-karlsruhe.de/WBS/sbr/publications/owl-metamodeling.pdf
3. Lecture Notes in Computer Science;S. Brockmans,2004
4. Chen, P.P.: The entity-relationship model – toward a unified view of data. ACM Transactions on Database Systems 1(1), 9–36 (1976)
5. Fowler, M.: UML Distilled, 3rd edn. Addison-Wesley, Reading (2004)