Differences of weighted differentiation composition operators from   Bloch-type space to weighted-type space
  We found several new equivalent characterizations for the boundedness and compactness of the differences of weighted differentiation composition operators from Bloch-type space to weighted-type space. Especially, we estimated its essential norm in terms of the $n$-th power of the induced analytic self-maps on the unit disk. 
Yu-Xia Liang
math.FA math.CV