Subsumption in Knowledge Graphs. - Mark Willems (PDK, 1991)

A Conceptual Semantics Ontology for Conceptual Graphs. - Mark Willems (ICCS, 1993)

A Logical Foundation for Verification. - Jan Treur; Mark Willems (ECAI, 1994)

Pragmatic Semantics by Conceptual Graphs. - Mark Willems (ICCS, 1994)

Formal Notions for Verification of Dynamics of Knowledge-Based Systems. - Jan Treur; Mark Willems (EUROVAV, 1995)

Projection and Unification for Conceptual Graphs. - Mark Willems (ICCS, 1995)

The REVISE Project: A Purpose Driven Method for Language Comparison. - Frances M. T. Brazier; Frank van Harmelen; Remco Straatman; Jan Treur; Niek J. E. Wijngaards; Mark Willems (EKAW, 1996)

Modelling an elevator design task in DESIRE: the VT example. - Frances M. T. Brazier; Pieter H. G. van Langen; Jan Treur; Niek J. E. Wijngaards; Mark Willems (Int. J. Hum. Comput. Stud., 1996)

Specification of Dynamics for Knowledge-Based Systems. - Pascal van Eck; Joeri Engelfriet; Dieter Fensel; Frank van Harmelen; Yde Venema; Mark Willems (Transactions and Change in Logic Databases, 1998)

Temporal Semantics of Compositional Task Models and Problem Solving Methods. - Frances M. T. Brazier; Jan Treur; Niek J. E. Wijngaards; Mark Willems (Data Knowl. Eng., 1999)

A Survey of Languages for Specifying Dynamics: A Knowledge Engineering Perspective. - Pascal van Eck; Joeri Engelfriet; Dieter Fensel; Frank van Harmelen; Yde Venema; Mark Willems (IEEE Trans. Knowl. Data Eng., 2001)

A semantical perspective on verification of knowledge. - Paul Leemans; Jan Treur; Mark Willems (Data Knowl. Eng., 2002)