1. Nonlinear Elliptic Boundary Value Problems and their Applications;Begehr,1996
2. First Order Elliptic Systems: A Function Theoretic Approach;Buchanan,1983
3. Nearness, accretivity and the solvability of nonlinear equations;Buica;Numer. Funct. Anal. Optim.,2002
4. Sistemi Ellittici in Forma Divergenza—Regolaritá All’interno;Campanato,1980
5. A history of Cordes condition for second order elliptic operators;Campanato,1983