1. Some free boundary problems with industrial applications;Fasano,1992
2. Existence and regularity for a minimum problem with free boundary;Alt;J. reine angew. Math.,1981
3. On free boundary problems for the Laplace equation, Seminars on analytic functions,I;Beurling,1957
4. Henrot A. & Seck D., Back to an old approach for a classical free boundary problem (to appear)