1. & (1984). Cluster analysis. Thousand Oaks, CA: Sage Publications.
2. (2000). Constructing user-centered websites: The early design phases of small to medium sites. [Online] http://psychology.wichita.edu/surl/usabilitynews/2W/webdesign.htm. Retrieved September 5, 2002.
3. & (1956). A taxonomy of educational objectives: Handbook I. The cognitive domain. New York: David McKay.
4. (1997). Multidimensional scaling. [Online] Available: http://www.analytictech.com/borgatti/mds.htm. Retrieved September 5, 2002.
5. & (1989). Designing an information retrieval interface based on children's categorization of knowledge: A pilot study. In & (Eds.), Managing information and technology: Proceedings of the 52nd annual meeting of the American Society for Information Science 2, October 29-November 2, 1989, Washington, DC (pp.81-94). Medford, NJ: Learned Information.