- Financial Times (1999)
- Journal of Economic Perspectives 8(1):3--22 (1994)
- Brookings Institution Press, Washington, DC, (2001)
- P. Lang, Frankfurt am Main and New York, (1997)
- Journal of Economic Perspectives 8(1):23--44 (1994)
- Amsterdam 1999: OECD Work on Measuring Intangible Investment, OECD, (1999)
- Report, Organisation for Economic Co-operation and Development OECD, Paris, (1998)
- Economics of Innovation and New Technology 17(4):377--400 (2008)


user