1953 Yugoslavia, Trieste Zone B First Day Cover - The 38th Esperanto Congress, Zagreb - Yugoslav Postage Stamp in Changed Color and Overprinted "STT - VUJNA" 15Din & 300 Din tied by ' KOPER CAPODISTRIA d. 31. VII.53' signed certificate by Caffaz Perito Filatelico, 2006.
Mi:YU 729,-730; Yt:YU 638-639, SG:YU 755-756.