1. Milgate, M. Goods and commodities. In Palgrave’s New Dictionary of Economics Vol. II (eds Eatwell, J. et al.) (Macmillan and Co., London, 1987).
2. Blümel, W., Pethig, R. & von dem Hagen, O. The theory of public goods: A survey of recent issues. J. Institut. Theor. Econ. (JITE) 142, 241–309 (1986).
3. Cowen, T. Public goods. In Concise Encyclopedia of Economics 2nd edn (ed. Henderson, D. R.) (Library of Economics and Liberty, Indianapolis, 2008).
4. Ostrom, E. Governing the Commons: The Evolution of Institutions for Collective Action (Cambridge University Press, Cambridge, 1990).
5. Hardin, G. The tragedy of the commons. Science 162, 1243–1248 (1968).