Liouville theorems, Volume growth, and volume comparison for Ricci   shrinkers
  In this paper, we study volume growth, Liouville theorem and the local gradient estimate for $f$-harmonic functions, and volume comparison property of unit balls in complete noncompact gradient Ricci shrinkers. We also study integral properties of f-harmonic functions and harmonic functions on such manifolds. 
Li Ma
math.DG math.AP