Soviet Zone Bezirk Overprints

In 1948 the separation between East and West Zones hardened and currency reform took place in the West with the creation of the DM. Existing Worker and Numeral stamps of the Allied Zones received "posthorn" overprints in the West, to prevent use of stamps purchased in the East. As a countermeasure, the Soviets overprinted their stocks of stamps with a district number ("OPD-Bezirk") number. There, each town in each district did their own overprinting. These can be collected simply as the basic stamp (like the corresponding Western "posthorn" overprints), or by the Bezirk number (ten different; the numbers relate to the old administrative numbers of the German Reich, so in the Soviet Zone were limited to only ten numbers between 3 and 41), or by all the individual towns and postal district (over 1000 possibilities).
The ten Bezirk districts were as follows :
3 : Berlin (only those parts in the Soviet sector)
14 : Dresden
16 : Erfurt
20 : Halle
27 : Leipzig
29 : former Magdeburg (now joined with Halle)
36 : Potsdam
37 : Schwerin
38 : part of former Stettin (now joined with Schwerin)
41 : former Chemnitz (now joined with Leipzig)

For a listing of the individual towns, see Michel Specialised.
For a detailed study of the overprints and their use, see Modry/Rehfeld "Bezirksstempelaufdruckmarken", and also "Handbuch" by the Arbeitsgemeinschaft Bezirksstempelaufdrucke SBZ 1948.