1916 DEAD LETTER OFF. PRAGUE / undeliverable letter from Liberec to Jablonec officially opened in Prague dead letter off. to find out the sender, CDS REICHENBERG 9/ 4.XI.16, transit and arrival postmark, rare stick-on label OŠTOVNÍ ÚŘAD ÚLOŽNÝ U C.K. ŘEDITELSTVÍ POŠT A TELEGRAFŮ V PRAZE; very fine