APA (7th ed.) Citation

United States. Postmaster General. (1928). Improper return of undeliverable double post cards. U.S. GPO.

Chicago Style (17th ed.) Citation

United States. Postmaster General. Improper Return of Undeliverable Double Post Cards. Washington: U.S. GPO, 1928.

MLA (9th ed.) Citation

United States. Postmaster General. Improper Return of Undeliverable Double Post Cards. U.S. GPO, 1928.

Warning: These citations may not always be 100% accurate.