1. Allen, T.F.H. and Starr, T.B. (1982), Hierarchy. Perspectives for Ecological Complexity, The University of Chicago Press, Chicago, IL.
2. Amsterdamski, S. (1981), “Riduzione”, in Enciclopedia Einaudi, Einaudi, Torino, pp. 62‐75.
3. Ashby, W.R. (1956), An Introduction to Cybernetics, Chapman & Hall Ltd, London.
4. Ashby, W.R. (1968), “Principles of the self‐organizing system”, in Buckley, W. (Ed.), Modern Systems Research for the Behavioral Scientist, Aldine Publishing Company, Chicago, IL, pp. 108‐18.
5. Ayala, F.J. and Dobzhansky, T. (Eds) (1974), Studies in the Philosophy of Biology, The Macmillan Press Limited, London.