Czechoslovakia was not very active on the philatelic market in terms of material. Only the official designs issued by the postal authorities of Czechoslovakia are available, and are very common to be found.

Set stamp covers:

The stamp issued during the Czechoslovakian week at the Fair has also only one design, however there are cancellations. The only difference is the letter used below PRAHA3: a or b. There is no information about if this cancellations were done or the covers were sold in Brussels or only in Czechoslovakia.