Hy. Chen et Wt. Tong, ON PROJECTIVE FREE PROPERTIES OF RINGS, Science in China. Series A, Mathematics, Physics, Astronomy & Technological Sciences, 39(2), 1996, pp. 177-186
Some new rings are introduced, and their projective free properties ar
e studied. Moreover, module structures of group rings are obtained, an
d Quillen-Suslin's Theorem is generalized.