APA (7. basım) Alıntı
United States Postal Service. The Postal Service Guide to U.S. Stamps: Updated Stamp Values (Vigésima octava edición.).
Chicago Style (17. basım) Atıf
United States Postal Service. The Postal Service Guide to U.S. Stamps: Updated Stamp Values. Vigésima octava edición.
MLA (9th ed.) Atıf
United States Postal Service. The Postal Service Guide to U.S. Stamps: Updated Stamp Values. Vigésima octava edición.
Uyarı: Bu alıntı herzaman %100 doğru olmayabilir..