Morrey Spaces and Fractional Integral Operators
  The present paper is devoted to the boundedness of fractional integral operators in Morrey spaces defined on quasimetric measure spaces. In particular, Sobolev, trace and weighted inequalities with power weights for potential operators are established. In the case when measure satisfies the doubling condition the derived conditions are simultaneously necessary and sufficient for appropriate inequalities. 
Eridani, Vakhtang Kokilashvili and Alexander Meskhi