References
Bignell, V. and Fortune, J. (1984) Understanding Systems Failures, Manchester, Manchester University Press.
Buzan, A. (1974) Use Your Head, London, BBC Publications.
Checkland, P. (1981) Systems Thinking, Systems Practice, London, Wiley.
Fisher, W. and Hudson, J. (1997) Using diagrams – a diagram , unpublished paper.