Russia, Airmail, 1932, 15k Dirigible Construction, engraved, imperf, right margin single, regummed, wide margins, bold color, Very Fine, a rare imperforate airmail variety, with only one sheet of the imperforate variety ever printed; with 2015 A.P.S. certificate. Michel No. 406 U. Scott No. C25c  $5,750 for o.g. $0 (Image)