Existence Results for a critical fractional equation
  We are concerned with existence results for a critical problem of Brezis-Nirenberg Type involving an integro-differential operator. Our study includes the fractional Laplacian. Our approach still applies when adding small singular terms. It hinges on appropriate choices of parameters in the mountain-pass theorem 
Hichem Hajaiej, Giovanni Molica Bisci and Luca Vilasi
math.AP