The Term Generating Power of Context-Free Hypergraph Grammars. - Joost Engelfriet; Linda Heyker (Graph-Grammars and Their Application to Computer Science, 1990)

The String Generating Power of Context-Free Hypergraph Grammars. - Joost Engelfriet; Linda Heyker (J. Comput. Syst. Sci., 1991)

Context-Free Hypergraph Grammars have the Same Term-Generating Power as Attribute Grammars. - Joost Engelfriet; Linda Heyker (Acta Informatica, 1992)

Context-Free Graph Languages of Bounded Degree are Generated by Apex Graph Grammars. - Joost Engelfriet; Linda Heyker; George Leih (Acta Informatica, 1994)

Hypergraph Languages of Bounded Degree. - Joost Engelfriet; Linda Heyker (J. Comput. Syst. Sci., 1994)