1. Director-General’s Opening Remarks at the Media Briefing on COVID-19
https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19
2. Assessing Risk Factors for Severe COVID-19 Illness;CDC,2020
3. A review on epidemiology, genomic characteristics, spread, and treatments of COVID-19;Bharati,2022
4. Symptoms of Coronavirus;Centers for Disease Control and Prevention
5. Clinical Care for Severe Acute Respiratory Infection: Toolkit: COVID-19 Adaptation
https://apps.who.int/iris/handle/10665/331736