References
- US Department of Homeland Security. Beyond the border: a shared vision for perimeter security and economic competitiveness. Available from: http://www.dhs.gov/beyond-border-shared-vision-perimeter-security-and-economic-competitiveness. [Accessed 9 November 2014].
- The World Bank. 2013. Military expenditure (% of GDP). Available from: http://data.worldbank.org/indicator/MS.MIL.XPND.GD.ZS. [Accessed 9 November 2014].