Diffusive fields in 3-D configurations, e.g., as those faced when searching for inclusions in conductive planar layered media (a metal slab, a half-space subsoil) at low frequencies, can be modeled via Green's integral formulations that require Green dyads. Such formulations make good use of extended Born approximations in order to express the secondary sources existing within the probed inclusion from the primary fields at same location. Here it is sketched how several such approximations perform in cases of interest by comparison with full solutions and benchmark measurements.