SMITH, Barry. Ontology and information systems [online]. [Buffalo (N.Y.), 2004 [cit. 2013-08-19]. 93 s. Paper based upon work supported by the National Science Foundation under Grant No. BCS-9975557 „Ontology and Geographic Categories“. State University of New York at Buffalo, Department of Philosophy. Dostupné z: http://ontology.buffalo.edu/ontology%28PIC%29.pdf.
Zpráva dostupná volně z univerzitního webu: http://ontology.buffalo.edu/ontology%28PIC%29.pdf.