One noticeable fact was that air-mail stamps appeared at rather frequent intervals.

The first stamp in this issue appeared on 1942-09-15.

It was amazing this, to watch those stamps appear as though conjured from nowhere.

Gachet's collector's stamp appears on the bottom edge of the print.

The next stamps appeared in 1921, after inflation had taken hold.

The first stamp, worth two kopecks, appeared on April 16, 1874.

The latest stamp comes from 2003 and appeared in North Korea.

Australia's first airmail-designated stamp appeared on 20 May 1929.

Five years later, two new stamps appeared to commemorate the 125th anniversary of the pictorials.

Additional stamps in the series appeared through the end of the century.