1. Global survey on geriatrics in the medical curriculum;Keller,2002
2. United Nations. World population prospects. Available at: http://www.un.org/esa/population/publications/wpp2000/chapter5.pdf. Accessed March 22, 2015.
3. Office for National Statistics. Interim life tables 2008-2010. Available at: http://www.ons.gov.uk/ons/rel/lifetables/interim-life-tables/2008-2010/index.html. Accessed March 22, 2015.
4. Office for National Statistics. 2011 Census - Population and Household Estimates for England and Wales, March 2011. Office for National Statistics. Available at: http://www.ons.gov.uk/ons/rel/census/2011-census/population-and-household-estimates-for-england-and-wales/stb-e-w.html. Accessed May 19, 2015.
5. Congress quarterly;Golden Years: How neurosurgeons are addressing an aging population,2013