TY  - JOUR
AU  - Chen, Xiaofa
AU  - Chen, Xiao-Wu
TI  - The lower extension groups and quotient categories
JO  - Comptes Rendus. Mathématique
PY  - 2019
SP  - 832
EP  - 840
VL  - 357
IS  - 11-12
PB  - Elsevier
UR  - http://www.numdam.org/articles/10.1016/j.crma.2019.11.006/
DO  - 10.1016/j.crma.2019.11.006
LA  - en
ID  - CRMATH_2019__357_11-12_832_0
ER  -