1. Incidence, management, and outcomes of end-stage renal disease in the elderly;Tamura;Curr Opin Nephrol Hypertens,2009
2. U.S. Census Bureau International database: Table 094. Midyear population, by age and sex http://www.census/gov.population/www/projections/natdet_D1A.html
3. United Nations Population Division: World population ageing 1950-2050 http://www.un.org/esa/population/publications/worldageing19502050/pdf/62executivesummary_english.pdf