1. United Nations. Ageing. https://www.un.org/en/global-issues/ageing; accessed May 2023.
2. Population Reference Bureau. https://www.prb.org/resources/countries-with-the-oldest-populations-in-the-world/; accessed May 2023.
3. World Population Ageing,2015
4. Bone and Joint Initiative USA, The Hidden Impact of Musculoskeletal Disorders on Americans, fourth ed. https://www.boneandjointburden.org/fourth-edition/about; accessed May 2023..