SAMIA CHALLAL. A Barrier Function for the Regularity of the Free Boundary in $div(a(x) \nabla u )=-(h(x)\gamma)_x$ with $h_x < 0$. International Journal of Mathematics And its Applications, [S. l.], v. 9, n. 4, p. 35–43, 2021. Disponível em: http://ijmaa.in/index.php/ijmaa/article/view/26. Acesso em: 25 apr. 2024.