1. Vorlesungen über Reele Funktionen;Carathéodory,1918
2. An envelope theorem for weak solutions of quasilinear elliptic boundary value problems;Carl,1996
3. On discontinuous implicit evolution equation;Carl;J. Math. Anal. Appl.,1998
4. On a second order discontinuous implicit boundary value problem;Carl;Nonlinear Stud.,1997
5. On discontinuous first order implicit boundary value problems;Carl;J. Differential Equations,1998