1. Gay, G., Hembrooke, H.: Activity-Centered Design: an Ecological Approach to Designing Smart Tools and Usable Systems. MIT Press, Cambridge (2004)
2. Fink, J., Kobsa, A.: User Modeling for Personalized City Tours. Artificial Intelligence Review 18(1) (2002)
3. Kobsa, A.: Generic User Modeling Systems. In: User Modeling and User-Adapted Interaction, vol. 11(1-2). Kluwer Academic Publishers, Dordrecht (2001)
4. Kobsa, A.: User Modeling: Recent Work, Prospects and Hazards. In: Adaptive User Interfaces: Principles and Practice. North Holland/Elsevier (1993)
5. Jung, C.G.: Psychological Types. Princeton University Press, Princeton (1971)