Fifth International Philatelic Exhibition Issues

Sixth International Philatelic Exhibition, Washington DC 1966, 5 cent SIPEX issue, Lawrence O'Brien, I have several of these souvenir sheets. APS

US #1311 MNH Souvenir Sheet SIPEX - Sixth International Philatelic Exhibition | United States, General Issue Stamp

1936-1937 National Postal Museum

A.A.A. Issue National Postal Museum

Sixth International Philatelic Exhibition Issue 5c 1966 issue U.S.

1310 SIPEX Jackson FDC

Chinese Resistance Issue

Pictorial Issues (1869-1870)

First Day Cover for SIPEX – All Artifacts – The John F. Kennedy

The Postal History of ICAO

Daniel F. Kelleher Auctions, LLC Sale - 691 Page 25

Grill Issues (1867-1868)