United States. Postmaster General. (1932). Improper acceptance of envelopes as post cards at 1-cent rate. U.S. GPO.
Chicago Style (17th ed.) CitationUnited States. Postmaster General. Improper Acceptance of Envelopes as Post Cards at 1-cent Rate. Washington: U.S. GPO, 1932.
MLA (9th ed.) CitationUnited States. Postmaster General. Improper Acceptance of Envelopes as Post Cards at 1-cent Rate. U.S. GPO, 1932.
Warning: These citations may not always be 100% accurate.