RATIBOR, German Reich official postal stationery card 20 Pfg dark blue, Prussia issue 1920, additional 20 Pfg dark violet-blue official April 1920, to Woinowit/OSz, double-circle RATIBOR 18 4 21 * * n (OS handbook no. 274.20), rare cancellation, unusual prohibited mixed franking, since continued use of German Reich stamps and postal stationery in plebiscite territory was not permitted, nevertheless not challenged by postal administration, age and use wear typical of period