APA (7th ed.) Citation

United States. Postmaster General. (1927). Improper use of air-mail stamps. U.S. GPO.

Chicago Style (17th ed.) Citation

United States. Postmaster General. Improper Use of Air-mail Stamps. Washington: U.S. GPO, 1927.

MLA (9th ed.) Citation

United States. Postmaster General. Improper Use of Air-mail Stamps. U.S. GPO, 1927.

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