@article{CRMATH_2019__357_11-12_832_0,
     author = {Chen, Xiaofa and Chen, Xiao-Wu},
     title = {The lower extension groups and quotient categories},
     journal = {Comptes Rendus. Math\'ematique},
     pages = {832--840},
     publisher = {Elsevier},
     volume = {357},
     number = {11-12},
     year = {2019},
     doi = {10.1016/j.crma.2019.11.006},
     language = {en},
     url = {http://www.numdam.org/articles/10.1016/j.crma.2019.11.006/}
}