What are "wicked problems?"
Rittel and Webber first identified the concept of "wicked problems" in 1973.
Rittel, H.W. & Webber, M.M. 1973, 'Dilemmas in a general theory of planning', Policy sciences, vol. 4, no. 2, pp. 155-69. (available full text via Business Source Complete) Also available on e readings for Subject 26100.