1. Patterson KD, Pyle GF (1991) The geography and mortality of the 1918 influenza pandemic. Bull Hist Med 65:4–21
2. World Health Organization (2020) WHO Coronavirus Disease (COVID-19) Dashboard. https://covid19.who.int/?gclid=Cj0KCQiA3smABhCjARIsAKtrg6LFStnmmzbtxGzUVwRhCxyEGNaqt6-OLCfw4S2J-gkFjd200n-I9lIaAiDzEALw_wcB Accessed Jan 27, 2021.
3. European Statistical System (2019). Population structure and ageing. Retrieved from https://ec.europa.eu/eurostat/statistics-explained/index.php/Population_structure_and_ageing
4. United Nations, Department of Economic and Social Affairs, Population Division (2019) World Population Ageing 2019: Highlights. Retrieved from https://www.un.org/en/development/desa/population/publications/pdf/ageing/WorldPopulationAgeing2019-Highlights.pdf
5. Hutton D and World Health Organization (2008) Older persons in emergencies: considerations for action and policy development. Retrieved from https://apps.who.int/iris/handle/10665/43817