APA (7th ed.) Citation

United States. Army. Air Corps. (1920). Standard test of Hercules spark plugs. U.S. GPO.

Chicago Style (17th ed.) Citation

United States. Army. Air Corps. Standard Test of Hercules Spark Plugs. Washington: U.S. GPO, 1920.

MLA (9th ed.) Citation

United States. Army. Air Corps. Standard Test of Hercules Spark Plugs. U.S. GPO, 1920.

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