中国科学院数学与系统科学研究院期刊网
The Category of Modules over a Triangular Matrix Ring of Order n and Its Homological Characterizations
Mei Hua SHI(1), Fang LI(2)
Acta Mathematica Sinica, Chinese Series . 2006, (1): 215 -224 .  DOI: 10.12386/A2006sxxb0028