Integration operators between Hardy spaces on the unit ball of CnCn

We completely describe the boundedness of the Volterra type operator JgJg between Hardy spaces in the unit ball of CnCn. The proof of the one dimensional case used tools, such as the strong factorization for Hardy spaces, that are not available in higher dimensions, and therefore other techniques must be used. In particular, a generalized version of the description of Hardy spaces in terms of the area function is needed.