Remark on the Fredholm alternative for nonlinear operators with application to nonlinear integral equations of generalized Hammerstein type Jindřich Nečas (1972) Commentationes Mathematicae Universitatis Carolinae
Riesz transforms and related singular integrals. Tadeusz Iwaniec, Gaven Martin (1995) Journal für die reine und angewandte Mathematik