1. Marković, S., Baar, T.: An OCL semantics specified with QVT. In: Nierstrasz, O., Whittle, J., Harel, D., Reggio, G. (eds.) Proceedings, MoDELS/UML 2006, Genova, Italy, October 1–6, 2006, vol. 4199, LNCS, pp. 660–674. Springer, Heidelberg (2006)
2. Rumbaugh J., Jacobson I., Booch G.: The Unified Modeling Language Reference Manual. Object Technology Series, 2nd edn. Addison-Wesley, Reading (2005)
3. Baar, T.: Correctly defined concrete syntax for visual models. In: Nierstrasz, O., Whittle, J., Harel, D., Reggio, G. (eds.) Proceedings, MoDELS/UML 2006, Genova, Italy, vol. 4199, LNCS, pp. 111–125. Springer, Heidelberg (2006)
4. Fondement, F., Baar, T.: Making metamodels aware of concrete syntax. In: Hartman, A., Kreische, D. (eds.) Proceedings of European conference on Model Driven Architecture (ECMDA-FA), vol. 3748, LNCS, pp. 190–204. Springer, Heidelberg (2005)
5. Costagliola G., De Lucia A., Orefice S., Polese G.: A classification framework to support the design of visual languages. J. Vis. Lang. Comput. 13(6), 573–600 (2002)