1. Safety First: Technology, Labor, and Business in the Building of American Work Safety 1879–1939;Aldrich,1997
2. Allgöwer, S., 2013. Facts, trends and stories on Integrated mobility’, Como, no. 10, Siemens, AG, Infrastructure & Cities Sector, Mobility and Logistics Division, Munich.
3. Ambler, SW & Associates, 2014. The agile system development life cycle (SDLC). viewed 26 March 2016, .
4. Disciplined Agile Delivery: a Practitioner's Guide to Agile Software Delivery in the Enterprise;Ambler,2012
5. Ambler, SW 2014. Examining the Agile Cost of Change Curve. Viewed 10 February 2016 .