Urkunden Prüfgebiet: USA (Unions-Ausgaben ab 1847)

Prüfer	Art des Attestes	Katalog	KatalogNr.
APS, (American Philatelic Society) (Prüferkommission)	Attest	Michel	28 A
Crowe, William T. (Sonstiges)	Attest	Scott	28 A
The Philatelic Foundation, (Prüferkommission)	Attest	Scott	295
The Philatelic Foundation, (Prüferkommission)	Attest	Scott	295 a
The Philatelic Foundation, (Prüferkommission)	Attest	Scott	30
The Philatelic Foundation, (Prüferkommission)	Attest	Scott	30 A
PSE, Professional Stamp Experts (Prüferkommission)	Attest	Scott	3054 e
Crowe, William T. (Sonstiges)	Attest	Scott	31