1. Statement in a radio programme ‘The engineer does what he likes; the user has a problem’;Wickstrøm
2. In search of excellence—lessons from America's best run companies;Peters,1982
3. Need assessment—a key to user-oriented product innovation;Holt,1984
4. Markedsorientert produktutvikling—metoder for behovsstudiet;Juhler,1986
5. The marketing edge;McBurnie,1987