1. E. Ginzberg: The mechanization of work, Sci. Am. 247(3), 66–75 (1982)
2. US Census Bureau: Value of Construction Put in Place – Seasonally Adjusted Annual Rate (U.S. Census Bureau, Washington DC 2012),
http://www.census.gov/
3. Bureau of Labor Statistics: Industries at a Glance: Construction: NAICS 23 (US Department of Labor, Washington DC 2012),
http://www.bls
. gov/iag/tgs/iag23.htm
4. US Census Bureau: Statistics of U.S. Businesses (U.S. Census Bureau, Washington DC 2012),
http://www.census.gov/csd/susb/
5. European Commission: Eurostat Regional Yearbook 2012 (Publications Office of the European Union, Luxembourg 2012),
http://ec.europa.eu/eurostat/web/products-statistical-books/-/KS-HA-12-001