1. Variational problems with two phases and their free boundaries,;H. W. Alt;\emph{Transactions of the American Mathematical Society},1984
2. Existence and regularity for a minimum problem with free boundary.,;H. Alt;\emph{J. Reine Angew. Math.},1981
3. In;J. Andersson;In preparation.
4. Multi-phase quadrature domains and a related minimization problem,;A. Arakelyan;\emph{Potential Analysis},2016
5. Existence of unbounded quadrature domains for the p-laplace operator,;F. Bahrami;\emph{Bulletin of Iranian Mathematical Society},1998