1. Genesereth, M. R. & Fikes, R. (1991). Knowledge Interchange Format, Version 2.2, Reference Manual. Logic 90-4, Logic Group, Stanford University, CA, USA.
2. Gruber, T. (1991a). The Role of Common Ontology in Achieving Shareable, Reusable Knowledge Bases. In Proceedings of the Second International Conference on Principles of Knowledge Representation and Reasoning, J. A. Allen,R. Fikes, & E. Sandewall (Ed.), Morgan Kaufmann.
3. Gruber, T. R. (1991b). Ontolingua: A Mechanism to Support Portable Ontologies. KSL 91-66, Knowledge Systems Laboratory, Stanford University, Stanford, CA, USA.
4. Mineau, G. W. (1991). Toward Compatible Primitive Sets. In Proceedings of the 6th Annual Workshop on Conceptual Structures, E. Way (Ed.), Binghamton, New York, USA: SUNY at Binghamton, pp. 53–65.
5. Mineau, G. W. (1993). Sharing Ontologies is Sharing Semantics. In: Proceedings of the First Workshop on Formal Ontology in Conceptual Analysis and Knowledge Representation. Padova, Italy. March 17–19.