1 / 2 Groschen postal stationery card with a rare cancellation by blue K2 "MARTEN 25 8 73 11-12", posted to Dortmund, photographic finding by Hansmichael Krug BPP "The rare stamp in blue color is clearly applied twice. The card to Dortmund is correctly franked with 1 / 2 Groschen according to the tariff valid from July 1, 1872... in flawless very good condition.