Weighted integral inequalities for the nontangential maximal function, Lusin area integral, and Walsh-Paley series R. Gundy; R. Wheeden — 1974 Studia Mathematica
Existence and estimates of Green's function for degenerate elliptic equations S. Chanillo; R. L. Wheeden — 1988 Annali della Scuola Normale Superiore di Pisa - Classe di Scienze