TY - JOUR T1 - 封一 JO - 中国数学会通讯 VL - 1 SP - 0 EP - 0 PY - 2020 DA - 2020/11 SN - 1 DO - http://doi.org/ UR - https://global-sci.org/intro/article_detail/cmsn/18449.html KW - AB -