12+3 Rpf. On 15 Pfg \"help in need 1931: buildings\", overprint error \"Rdf. Instead of Rpf. \" extremely rare printing error the only in few copies have become known is, in mint never hinged condition waren to the time the certifying including this piece only two examples known, expertized Georg Buehler (double signature), besides Richter as well photo expertize A. Schlegel BPP (2012) : \"the quality is perfect. \", the valuation by Michel catalogue becomes the rarity in no trap just.