50 Heller exhibition Pilsen with hand stamp overprint "we are free! plus swastika" with likewise overprinted upper margin of sheet, with full strike "Liberec 1 German Reichspost eighth of October 1958 Heil Hitler! " on piece, sound, expertized Osper BPP, photo expertize Brunel VP (2025) "the condition is perfect. stamps with overprinted margin of sheet are rare.