1. European Commission (2011) Roadmap to a Resource Efficient Europe. COM(2011)571 Final (European Commission, Brussels)
2. National Research Council (2008) Minerals, Critical Minerals, and the U.S. Economy (National Academy Press, Washington, DC)
3. Eurostat (2012) Sustainable Development Indicators (Statistical Office of the European Communities, Luxembourg)
4. OECD (2011) Towards Green Growth: Monitoring Progress (OECD Indicators) (Organisation for Economic Co-operation and Development, Paris)
5. UNEP (2011) Decoupling Natural Resource Use and Environmental Impacts from Economic Growth (United Nations Environment Programme, Nairobi)