1. Ehrig, H., Engels, G.: Towards a Module Concept for Graph Transformation Systems. Technical Report 93-34, Vakgroep Informatica, Rijksuniversiteit Leiden, October 1993
2. Ehrig, H., Größe-Rhode, M.: Functional Theory of Parameterized Specifications in a General Specification Framework. TCS 135 (1994), 221–266.
3. Ehrig, H., Habel, A., Kreowski, H.J., Parisi-Presicce, F.: From Graph Grammars to High Level Replacement Systems, LNCS 532, Springer, Berlin, 269–291
4. Ehrig, H.: Introduction to the Algebraic Theory of Graph Grammars, Springer LNCS 73 (1979), 1–69
5. Ehrig et al: Towards Distributed Graph Grammars, in [ENRR, 87], 86–98