On (n,d)-perfect rings
  In this paper, we introduce the notion of "(n,d)-perfect rings" which is in some way a generalization of the notion of "S-rings". After we give some basic results of this rings and we survey the relationship between "A(n) property" and "(n,d)-perfect property". Finally, we investigate the "(n,d)-perfect property" in pullback rings. 
A. Jhilal and N. Mahdou