https://mirrors.tuna.tsinghua.edu.cn/CRAN/ TUNA Team, Tsinghua University
http://mirrors.tuna.tsinghua.edu.cn/CRAN/ TUNA Team, Tsinghua University
https://mirrors.ustc.edu.cn/CRAN/ University of Science and Technology of China
http://mirrors.ustc.edu.cn/CRAN/ University of Science and Technology of China
https://mirrors.eliteu.cn/CRAN/ Elite Education
https://mirror.lzu.edu.cn/CRAN/ Lanzhou University Open Source Society
http://mirror.lzu.edu.cn/CRAN/ Lanzhou University Open Source Society
https://mirrors.tongji.edu.cn/CRAN/ Tongji University