Two 1938 Covers to Chile

 Both covers have receipt postmarks. Both flew by air, but we do not know which airline was used.

Several 1938 Covers to Switzerland

This selection includes combined use with commemoratives and the use of Air France and Via Condor flights.

1937 Covers to Sweden and Switzerland (One Each)

We don't know the airline for either of these covers. The one to Switzerland is one of the early 'Por Primer Avion', or 'by first plane available' covers in my collection. 

Several 1937 Covers to Germany

Three of these flew Via Condor, and the other two likely did as well. I find two possible plate varieties in this selection.

The break smudge lower left may be a plate variety. 

The smudge in the line above C or REPUBLICA may be a plate variety.

Several 1937 Covers to England and the United States

 One of these covers is from the days when Condor flew to England. That was about to change.