Theme : Esperanto 06

I reported earlier about old Sovjet stamps on this theme.
But in this post, I'd like to go deeper into a special issue of 1926.

From the 6th till the 9th of August 1926, the 6th international congress of Esperanto-Proletarians was held in Leningrad (now Saint Petersburg).

Except for the russian words "posta and CCCP", all other texts are in Esperanto.

6th international proletarians (6th)  Esperanto - Congress

On top of the stamp, you will see the green star (verda stelo), symbol of Esperanto, and "SAT"
Again, SAT is an esperanto abbreviation which stands for : "Sennacieca Asocio Tutmonda"
(world wide association of (the) nationless).

And there is even more to say about this stamp...
If you take a closer look to the oval, in which the monument of the Constitution is depicted, you will see something strange :

A lots of dots and dashes, ... in Morse-code :
telling us : "Proletaroj cxiulandaj unuigxu!" ... Proletarians of all countries (world wide) unite!
"cx = ĉ; gx = ĝ"

Truly, a stamp that has more to tell us then there is to see at first glance.