APA (7th ed.) Citation

United States. Post Office Department. (1928). Air mail service, change in schedule. GPO.

Chicago Style (17th ed.) Citation

United States. Post Office Department. Air Mail Service, Change in Schedule. [Washington]: GPO, 1928.

MLA (9th ed.) Citation

United States. Post Office Department. Air Mail Service, Change in Schedule. GPO, 1928.

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