For more details please do also check my print publication "Holograms on Stamps"

On May 5th, 1993 the German, Swiss and Austrian postal service brought out a joint issue for the newly established international organisation „EURO-Regio“ for Lake Constance. Lake Constance is Europe’s biggest fresh water reservoir and is under special nature preserve protection. This is what the stamp issue commemorates. The three identically designed stamps of all the countries show the recently restored paddle-wheel steamboat „Hohentwiel“ and the flags of Austria, Germany and Switzerland. On the day of issue the German Postal Service (Postdienst - Deutsche Bundespost: Direktion Freiburg) produced a number of hologram folders bearing the cancelled stamp and a hologram on the outside. The hologram shows the geographical region of Lake Constance with all major cities and the surrounding Alpine mountains.
 
 
 

Inside of folder see below (original size is 20,8 cm  by 29 cm)