1. André, E., Rist, T., Müller, J.: WebPersona: A Life-Like Presentation Agent for the World-Wide Web. Knowledge-based Systems 11(1) (1998) 25–36
2. Bonar, J., Cunningham, R., Schultz, J.: An Object-Oriented Architecture for Intelligent Tutoring Systems. In: OOPSLA’86 Proceedings (1986) 269–276
3. Booch, G., Rumbaugh, J., Jacobson, I.: The Unified Modeling Language User Guide. Addi-son Wesley (1999)
4. Gamma, E., Helm, R., Johnson, R., Vlissides, J.: Design Patterns-Elements of Reusable Object-Oriented Software. Addison-Wesley (1995)
5. Geib, C., Levison, L., Moore, M. B.: SodaJack: an architecture for agents that search for and manipulate objects. Technical Report MS-CIS-94-16 / CINC-LAB 265. Dept. of Computer and Information Science, University of Pennsylvania (1994)