@inproceedingsNagl_Engels_Gall_Schäfer_1983, place=Berlin/Heidelberg, series=LNCS, title=Software Specification by Graph Grammars, volume=153, DOI=dx.doi.org/10.1007/BFb0000113, booktitle=Proceedings of the 2nd International Workshop on Graph-Grammars and Their Application to Computer Science, Osnabrück (Germany), publisher=Springer, author=Nagl, Manfred and Engels, Gregor and Gall, Rupert and Schäfer, Wilhelm, year=1983, pages=267–287, collection=LNCS 
LibreCat: /record/8255
DOI: dx.doi.org/10.1007/BFb0000113

@articleEngels_Gall_Nagl_Schäfer_1983, title=Software Specification Using Graph Grammars, volume=31, DOI=http://dx.doi.org/10.1007/BF02251236, number=4, journal=Computing, author=Engels, Gregor and Gall, Rupert and Nagl, Manfred and Schäfer, Wilhelm, year=1983, pages=317–346 
LibreCat: /record/7411
DOI: http://dx.doi.org/10.1007/BF02251236

@articleEngels_Pletat_Ehrich_1983, title=An Operational Semantics for Specifications of Abstract Data Types with Error Handling, volume=9, DOI=http://dx.doi.org/10.1007/BF00265557, number=3, journal=Acta Informatica, author=Engels, Gregor and Pletat, Udo and Ehrich, Hans-Dietrich, year=1983, pages=235–254 
LibreCat: /record/7412
DOI: http://dx.doi.org/10.1007/BF00265557

@inproceedingsEngels_Schäfer_1982, place=München/Leipzig, title=Specification of a Programming Support Environment by Graph Grammars, booktitle=Proceedings of the conference on Graphtheoretic Concepts in Computer Science (WG), München (Germany), publisher=Hanser, author=Engels, Gregor and Schäfer, Wilhelm, year=1982, pages=47–62 
LibreCat: /record/7811

@inproceedingsPletat_Engels_Ehrich_1982, title=An Operational Approach to Conditional Algebraic Specifications, volume=82, booktitle=Proceedings of the 7eme Colloque sur les Arbres en Algebre et en Programmation, Lille (France), author=Pletat, Udo and Engels, Gregor and Ehrich, Hans-Dietrich, year=1982, pages=254–270 
LibreCat: /record/7812

@bookEngels_Pletat_Ehrich_1981, title=Handling Errors and Exceptions in the Algebraic Specifications of Data Types, publisher=University of Osnabrück, author=Engels, Gregor and Pletat, Udo and Ehrich, Hans-Dietrich, year=1981 
LibreCat: /record/8184

@bookPletat_Engels_Ehrich_1981, title=Operational Semantics of Algebraic Specifications with Conditional Equations, publisher=University of Dortmund, Department of Computer Science, author=Pletat, Udo and Engels, Gregor and Ehrich, Hans-Dietrich, year=1981 
LibreCat: /record/8185