Issue n° 13 - 1968
Number of countries : 18
Debuting countries : none
Returning countries : none
Withdrawing countries : Norway
Common design : a key with the CEPT logo as handle, said to open the door to a United Europe.
Countries using their own design : Liechtenstein (their design is slighly different, their key bittings are shaped as an E)
Designer : Hans Schwarzenbach (Switzerland)
Note : Most stamps issued in March and late April.