The FDC's which have been issued are to be split into the FDC for the set of stamps and the FDC for the souvenir sheet.

The official issuing date is 17 April, any different date of the 17 April is known but is not the official FD cancellation.

FDC about the set of stamps. There are 2 types of FDC covers known with a specific design and there are also known of a common FDC design for the issue of stamps in Spanish.

Design 1: 

Design 2, which has been printed by Rodan, Belgium and exists in 2 colors blue and black (front and back)

Common design:

for the Souvenir Sheet, there is one official design and also the same cover of the first design of the FDC for the set of stamps and which has been put on a larger cover:

Design 1:

The following cover is a so-called FDC cover but which has been cancelled on 2nd of May and which was a common cancellation: