1. Dau, F.: The Logic System of Concept Graphs with Negations and its Relationship to Predicate Logic. PhD-Thesis, Darmstadt University of Technology (2002);
2. To appear in Springer Lecture Notes on Computer Science
3. Chein, M., Mugnier, M.-L.: Conceptual Graphs: Fundamental Notions. Revue d’Intelligence Artificielle 6, 365–406 (1992)
4. LNAI;M.-L. Mugnier,2000
5. Ganter, B., Wille, R.: Formal Concept Analysis: Mathematical Foundations. Springer, Heidelberg (1999)