a device for mounting planar lighting sources having a light emitting surface on a substrate includes a frame provided with fixing formations for fixing the frame on the substrate with the planar lighting source sandwiched between the frame and the substrate . the frame has an opening to surround the light emitting surface of said lighting source and is provided with elastic formations to elastically urge the lighting source toward the substrate . the fixing formations include at least one resilient formation to resiliently urge the frame toward the substrate .