Studer, R.G. (1970). 'The Dynamics of Behaviour-Contingent Physical Systems', in Proshansky, H.M., Ittleson, W.H. and Rivlin, L.G. (eds). Environmental Psychology: Man and his Physical Setting. New York: Holt Reinhart Winston.
... Studer's paper is rather difficult to follow because of his use of mathematical symbols. The general idea, however, is easy to understand. It is a useful model for dealing with mutual causal systems and 'wicked' problems....
1. Le Grew, D., Watson, D., Crawshaw, B., Itami, R. and Seddon, G. (1980). Creative Problem-Solving and Environmental Management. Melbourne: Centre for Environmental Studies.