In this paper we continue our study, started in , on the regularity theory of Stefan-like free boundary problems for a special class of fully nonlinear equations of parabolic type. We prove that degenerate Lipschitz free boundaries, with small Lipschitz constant in space, are $C^1$.
Emmanouil Milakis. "Fully nonlinear phase transition problems with flat free boundaries." Differential Integral Equations 23 (1/2) 93 - 112, January/February 2010. https://doi.org/10.57262/die/1356019389