@inproceedings{GG-1990-Barthelmann,
	author        = "Klaus Barthelmann",
	booktitle     = "{Proceedings of the Fourth International Workshop on Graph-Grammars and Their Application to Computer Science}",
	doi           = "10.1007/BFb0017384",
	editor        = "Hartmut Ehrig and Hans-Jörg Kreowski and Grzegorz Rozenberg",
	isbn          = "3-540-54478-X",
	pages         = "98--112",
	publisher     = "{Springer-Verlag}",
	series        = "{Lecture Notes in Computer Science}",
	title         = "{Describing Göttler’s Operational Graph Grammars with Pushouts}",
	volume        = 532,
	year          = 1990,
}