1. Adam Smith (1776), An Inquiry into the Nature and cause of Wealth of Nation and Book IV as quoted in Peter Groenwegon (1987) and (2008), Political economy and economy as an inquiry into the nature and causes of the wealth of nation.
2. Albert Humphrey (2005), SWOT Analysis for Management Consulting, SRI Alumni Newsletter (SRI International).
3. Backhouse, Roger, E., and Steven Medema(2008), definition of Economic, The New Palgrave Dictionary of Economics, 2rd Edition, pp.720-22.
4. Claes Lykke Ragner (2008), The Northern Sea Route, Published in Swedish in the Norden Association's Yearbook for 2008:.
5. DE, P., Ghosh, B. (2003), Causality between Performance and Traffic: An Investigation with Indian Port, Maritime Policy and Management, Vol. 30, no. 1, pp.5-27.