Commutators and Sobolev spaces
  This paper was withdrawn by arXiv admin because it plagiarizes "Chen, Wen Gu(PRC-BIAP); Lu, Shan Zhen(PRC-BJN) The commutators of fractional integrals on Besov spaces. Acta Math. Sin. (Engl. Ser.) 20 (2004), no. 3, 405--414." 
Sadek Gala