4[2]Nastasescu C,Raianu S,Oystaeyen F.Modules graded by G-set[J].Math Z,1990,203(4):605-627.
5[3]Cohen M,Montgomery S.Group-graded rings,smash products and group actions[J].T A M S,1984,282(1):237-258.
6[5]Anh PN and Marki Li.Morita equivalence for rings without identity[J].Tsukuba J,1987,11:1-16.
7刘绍学,Perspectives in ring theory,1988年
8Nǎstasscu, C. & Van Oystaeyen, F., Graded ring theory [M], Math. Library, Vol. 28,North Holland, 1982.
9Liu Shaoxue & Van Oystaeyen, F., Group graded rings, smash product and additive category [A], Perspective in Ring Theory [M], Kluwer Academic Publishers, 1988, 299- 310.