Persistence of undercompressive phase boundaries for isothermal Euler equations including configurational forces and surface tension. Math. Meth. Appl. Sci., (39)18:5409--5426, 2016. [PUMA: Kreiss Kreiss�Lopatinskii? adjoint condition, energy estimate, interface, linearized liquid-vapor problem stability, symmetrizer, uniform vorlaeufig well-posedness,] URL