S Tian, N Hu, J Lou, K Chen, X Kang, Z Xiang, H Chen… - Journal of infection, 2020 - Elsevier
… COVID-19 infected by Beijing emergency medical service. Among of 262 patients, 46 (17.6%)
were severe cases, 216 (82.4%) were common cases, which including 192 (73.3%) mild …