1. He W, Goodkind D, Kowal PR. An aging world: 2015 (US Census Bureau, international population reports); 2016.
2. Roberts AW, Ogunwole SU, Blakeslee L, Rabe MA. The population 65 years and older in the United States: 2016: US Department of Commerce, economics and statistics administration, US …; 2018.
3. Ortman JM, Victoria Velkoff A, Hogan H. An aging nation: the older population in the United States, current population reports. Washington, D.C: US Census Bureau, Washington, DC; 2014.
4. From the Centers for Disease Control and Prevention. Public health and aging: trends in aging--United States and worldwide. Jama. 2003;289(11):1371–3..
5. Wiener JM. Population aging in the United States of America: implications for public programmes. Int J Epidemiol. 2002;31:776.