Air mail. 15 c - postal stamp - public domain postal stamp scan

US 4c 5c 6c 7c 8c 10c 11c 13c 15c Air Mail Lot of 16 Used Postage Nice Set-#2107

Big Blue 1840-1940: Tunisia

C8 - 1926 15c Airmail Perf 11 - Mystic Stamp Company

125 Stamps of the united states Images: PICRYL - Public Domain Media Search Engine Public Domain Search

Aviation 15 Cent Denomination US Back of Book Air Mail Stamps for sale

File:USSR 1932-09-15 registered postal cover Leningrad-Berlin.jpg - Wikimedia Commons

C35 Airmail stamp 15c - postal stamp - PICRYL - Public Domain Media Search Engine Public Domain Search

125 Stamps of the united states Images: PICRYL - Public Domain Media Search Engine Public Domain Search

File:Lindbergh Airmail Stamp c10.jpg - Wikipedia

File:The United States 1949 Mi 601 stamp (75th anniversary of the UPU. Post office department in Washington, D.C. UPU emblem).jpg - Wikipedia

17 1947 Stamps Of The United States Image: PICRYL - Public Domain Media Search Engine Public Domain Search}

Stamp. USSR. Revenue stamps Soviet

US 4c 5c 6c 7c 8c 10c 11c 13c 15c Air Mail Lot of 16 Used Postage Nice Set-#2107