References
  1. The National Archives and Records Administration, Government of US: The deadly virus – Influenza epidemic of 1918. Available at : https://www.archives.gov/exhibits/influenza-epidemic/ . Accessed on 22 April 2020.
  2. World Health Organization: Bugs, drugs, smoke: Chapter 1 – Smallpox: Eradicating an ancient scourge. Available at https://www.who.int/about/bugs_drugs_smoke_chapter_1_smallpox.pdf. Accessed on 22 April 2020.
  3. World Health Organization: Coronavirus disease (COVID-2019) situation reports. Available at https://www.who.int/emergencies/diseases/novel-coronavirus-2019/situation-reports . Accessed on 24 April 2020.
  4. World Health Organization: Managing Epidemics-Key facts about major deadly diseases. Available at https://www.who.int/emergencies/diseases/managing-epidemics-interactive.pdf . Accessed on 22 April 2020.