1. Knowledge Interchange Format (KIF),
http://logic.stanford.edu/kif/kif.html
2. Ontolingua,
http://www.ksl.stanford.edu/software/ontolingua/
3. Yamaguchi, T.: Constructing Domain Ontologies Based on Concept Drift Analysis. In: IJCAI 1999, Workshop on Ontologies and Problem-Solving Methods (1999)
4. CommonKAD
http://www.commonkads.uva.nl/frameset-commonkads.html
5. Protégé,
http://protege.stanford.edu/