Calder\'on-Zygmund operators and commutators in spaces of homogeneous   type: weighted inequalities
  The recent proof of the sharp weighted bound for Calder\'on-Zygmund operators has led to much investigation in sharp mixed bounds for operators and commutators, that is, a sharp weighted bound that is a product of at least two different $A_p$ weight constants. The reason why these are sought after is that the product will be strictly smaller than the original one-constant bound. We prove a variety of these bounds in spaces of homogeneous type, using the new techniques of Lerner, for both operators and commutators. 
Theresa C. Anderson and Wendol\'in Dami\'an
math.CA