Stein neighborhoods of real surfaces in complex surfaces.

Let S be a real surface in a complex surface X, having only
isolated complex points, that are either elliptic or hyperbolic. It is known by a result of Bishop that the presence of elliptic points prevents the surface from having small Stein neighborhoods. We will give a construction of Stein neighborhood basis for surfaces having only hyperbolic complex points, but satisfying an extra condition of flatness.