1. Bureau of Economic Analysis (2009), Fixed Assets Accounts Tables, see: http://www.bea.gov/national/FA2004/SelectTable.asp.
2. Trends in multifactor productivity, 1948–1981;Bureau of Labor Statistics,1983
3. Labor composition and U.S. productivity growth, 1948–1990,” bureau of labor statistics bulletin 2426;Bureau of Labor Statistics,1993
4. Conference Board (2010), Total Economy Data Base, see: http://www.conference-board.org/economics/database.cfm.
5. European Commission, EU KLEMS Data Set, see: http://www.euklems.net/.