中国科学院数学与系统科学研究院期刊网
Strongly Graded Rings and Ungraded Module Categories
Jian Hua SUN,Shang Zhi LI
Acta Mathematica Sinica, Chinese Series . 2003, (6): 1103 -111 .  DOI: 10.12386/A2003sxxb0147