1. Beer, S.: 1989, ‘The Viable System Model: Its Provenance, Development, Methodology and Pathology’, in Espejo, R. and R. Harndon (eds.),The Viable System Model, John Wiley & Sons, New York.
2. Bickhard, M.H.: 1993,Representational Content in Humans and Machines,J. Expt. Theor. Artif. Intell. 5, 285–333.
3. Cam, P.: 1984, ‘Consciousness and Content-formation’,Inquiry 27, 381–397.
4. Churchland, P.S.: 1986,Neurophilosophy, MIT Press, Cambridge Mass.
5. Cummins, R.: 1984, ‘Functional Analysis’, in E. Sober (ed.),Conceptual Issues in Evolutionary Biology, MIT Press, Cambridge, pp. 386–407.