1. Clinical characteristics of coronavirus disease 2019 in China;Guan;N Engl J Med,2020
2. WHO/Europe | Coronavirus disease (COVID-19) outbreak — WHO announces COVID-19 outbreak a pandemic. http://www.euro.who.int/en/health-topics/health-emergencies/coronavirus-covid-19/news/news/2020/3/who-announces-covid-19-outbreak-a-pandemic. [Accessed 27 April 2020].
3. WHO coronavirus disease (COVID-19) dashboard,2020