On the Frechet Differentiability of Free Boundary Operator for a Muskat Type Problem. Journal of Partial Differential Equations, [S. l.], v. 2, n. 1, p. 71–94, 1989. Disponível em: https://staging.gsp.tricubic.dev/jpde/article/view/3614. Acesso em: 18 mar. 2026.