%0 Journal Article %T Maximal potentials, maximal singular integrals, and the spherical maximal function %A Piotr Hajlasz %A Zhuomin Liu %J Mathematics %D 2013 %I arXiv %X We introduce a notion of maximal potentials and we prove that they form bounded operators from $L^p$ to the homogeneous Sobolev space $\dot{W}^{1,p}$ for all $n/(n-1)