1. Ackoff, R. L. (1971). Towards a system of systems concepts.Manage. Sci. 17, 11.
2. Ashby, W. R. (1956).An Introduction to Cybernetics, Chapman & Hall, London.
3. Biotechnology: Report of a Joint Working Party (1980). Her Majesty's Stationary Office, London, March.
4. Celltech Group pic (1988). Annual Report, Celltech.
5. Checkland, P. B. (1981).Systems Thinking, Systems Practice, Wiley, Chicester.