There were two official Maximum Cards, which were issued during the official First Day of 18 March 1958 for the set of stamps of Liechtenstein.
There is a single card cancelled on 17 April 1958 which is described under the First Day Covers section (see previous menu item).
Official set with the official reference to the Expo 58 and its set of 2 stamps:
The official set of Maximum cards (here the same stamp is issued):
