A new approximation theory which unifies spherical and Cohen-Macaulay   approximations
  This paper gives a new approximation theory for finitely generated modules over commutative Noetherian rings, which unifies two famous approximation theorems; one is due to Auslander and Bridger and the other is due to Auslander and Buchweitz. Modules admitting such approximations shall be studied. 
Ryo Takahashi