1. Guarino, N., Masolo, C., Vetere, G.: OntoSeek: Content-Based Access to the Web. IEEE Intelligent Systems, 70–80 (1999)
2. Woods, W.A.: Conceptual Indexing: a better way to organize knowledge. Technical Report SMLI TR-97-61, Sun Microsystems Laboratories, Mountain View, CA (1997)
3. Haav, H.-M., Lubi, T.-L.: A Survey of Concept-based Information Retrieval Tools on the Web. In: Caplinkas, A., Eder, J. (eds.) Advances in Databases and Information Systems, 5th East-European Conference ADBIS*2001, vol. 2, Vilnius ”Technika”, pp. 29–41 (2001)
4. Kiryakov, A., et al.: Semantic Annotation, Indexing, and Retrieval. Elsevier’s Journal of Web Semantics 2(1) (2005)
5. Lecture Notes in Computer Science;E. Bozsak,2002