I acquired this airmail cover sent in 1947 from Greece to the USA.
Two different kind of stamps were used.
First the overcharged stamp "1-9-1946" concerning the reinstatement of King George II :
https://colnect.com/en/stamps/stamp/59564-Reinstatement_of_King_George_II-Greek_Kings_and_Queens-Greece
And additional postage with the surcharged stamps issued in 1947 due to the pasing away of King George II :
https://colnect.com/en/stamps/stamp/59668-Mourning_Issue_for_the_death_of_King_George_II-Greek_Kings_and_Queens-Greece
This stamps was only to be issued between April and December 1947, so this cover was sent in this period.
Those airmail stickers from Greece are great...(btw does th greek texte translate as Aeronotica?)
