United States. Postmaster General. (1925). Dutiable articles in regular (letter) mails to foreign countries. U.S. GPO.
Chicago Style (17th ed.) CitationUnited States. Postmaster General. Dutiable Articles in Regular (letter) Mails to Foreign Countries. Washington: U.S. GPO, 1925.
MLA (9th ed.) CitationUnited States. Postmaster General. Dutiable Articles in Regular (letter) Mails to Foreign Countries. U.S. GPO, 1925.
Warning: These citations may not always be 100% accurate.