Association between population density and infection rate suggests the importance of social distancing and travel restriction in reducing the COVID-19 pandemic. - Yin, Heliang; Sun, Tong; Yao, Lan; Jiao, Yan; Ma, Li; Lin, Lin; Graff, J Carolyn; Aleya, Lotfi; Postlethwaite, Arnold; Gu, Weikuan; Chen, Hong (Environmental Science & Pollution Research, 2021)