1. Bevan, N.: Personal Communication (2001)
2. Hassenzahl, M.: The thing and I: understanding the relationship between user and product. In: Blythe, M., Overbeeke, C., Monk, A.F., Wright, P.C. (eds.) Funology: From Usability to Enjoyment, pp. 31–42. Kluwer, Dordrecht (2003)
3. ISO/IEC 13407:1999. Human-Centred Design Processes for Interactive Systems (1999)
4. ISO/TR 16982:2002. Ergonomics of Human-System Interaction – Usability Methods Supporting Human Centred Design (2002)
5. ISO/PAS 18152:2003. Ergonomics of Human-System Interaction – Specification for the Process Assessment of Human-System Issues (2003)