3[1]Guarino N. Formal Ontology and Information System. www.ladseb.pd.cnr.it/infor/Ontology/Papers/FOIS98.pdf,2002.
4[2]IEEE Working Group P1600.1.IEEE Standard Upper Ontology(draft proposal). http://ontology.teknowledge.com/#introduction,2002.
5[3]Chandrasekaran B,Josephson JR. What are Ontologies,and Why do We Need Them? [J]. IEEE Intelligent Systems,1999,14(1):20-26.
6[4]Niles I,Pease A. Origins of the IEEE Standard Upper Ontology. http://reliant.teknowledge.com/HPKB/about/Pease.html,2002.
7[5]Gruber T. Towards Principles for the Design of Ontologies Used for Knowledge Sharing. http://ksl.stanford.edu/pub/KSL_Reports/KSL-93-04.tex.gz,2002.
8[6]Gruber T. A Translation Approach to Portable Ontology Specificatons. http://ksl.stanford.edu/pub/KSL_Reports/KSL-92-71.tex.gz,2002.
9[7]Gruber T. The Role of Common Ontology in Achieving Sharable,Resuable Knowledge. http://ksl.stanford.edu/pub/KSL_Reports/KSL-91-10.tex.gz,2002.
