Souvenir sheets issue "export fair Hanover, 30 Pfg dark greenish blue - rarest color variety, tied by special cancel "Hanover 21.5.49.--8" on the occasion of the technical export fair, photo expertize Andreas Schlegel BPP (2003) : "souvenir sheet and stamp are genuine. The condition is perfect, the slight bias cut is manufactured. ", Michel 7.500.- - very rare!