12 pfennigs "work slow-moving in the Un German undemocratic republic" as vertical pair on commercial letter with machine cancel "BERLIN N4 20.1. " to Berlin Friedenau with forwardings to Berlin Nikollasee with corresponding postmarks and note reverse, cover once folded and above with tape traces, stamps sound, Michel 1.800.-, provenance: 356. Auction Heinrich Koehler (2013)