1. Encyclopedia Britannica. Dicitionary and Thesaurus,
http://www.britannica.com/
2. Soltenborn, C.: Analysis of UML Workflow diagrams with dynamic Meta Modeling Techniques, Master’s Thesis, University of Paderborn, Germany (2006)
3. OMG Unified Modeling Language: Superstructure (final adopted spec, version 2.0), Technical report, Object Management Group (2003).
4. Lecture Notes in Computer Science;L. Baresi,2002
5. Baresi, L., Rafe, V., Spoletini, P., Rahmani, A.T.: An Efficient Model Checking Approach for Graph Transformation Systems. In: Proceedings of 3th Int. Workshop on Graph Transformation for Verification and Concurrency (GT-VC 2007) (2007)