Italy Airmail, 1928 Nobile Polar Exploration Semi-Official Error. Margin pair, front with black overprints normal, reverse with tête-bêche black overprints, only one sheet believed to have been recorded, one stamp with tiny paper adhesion, both stamps signed in pencil, o.g., never hinged, Very Fine and rare. Sanabria No. S4c var. Estimate  $400 - 600. $0 (Image)