1. On the qualitative theory of parametrized families of free boundaries;Acker;J. Reine Angew. Math.,1989
2. Uniqueness theorems for surfaces in the large V;Alexandrov;Vestn. Leningr. Univ.,1958
3. Existence and regularity for a minimum problem with free boundary;Alt;J. Reine Angew. Math.,1981
4. A Primer of Nonlinear Analysis;Ambrosetti,1983
5. On Free-Boundary Problems for the Laplace Equation;Beurling,1957