APA način citiranja (7. izdanje)
Associated Collectors of El Salvador & Freer, B. P. El Salvador Postal Stationery Handbook: Section 1 - Postcards.
Čikaški stil citiranja (17. izdanje)
Associated Collectors of El Salvador i B. Phillips Freer. El Salvador Postal Stationery Handbook: Section 1 - Postcards.
MLA način citiranja (9. izdanje)
Associated Collectors of El Salvador i B. Phillips Freer. El Salvador Postal Stationery Handbook: Section 1 - Postcards.
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