APA (7th ed.) Citation

United States. Army. Air Corps. (1921). Report on standard test of A.C. spark plugs. U.S. GPO.

Chicago Style (17th ed.) Citation

United States. Army. Air Corps. Report on Standard Test of A.C. Spark Plugs. Washington: U.S. GPO, 1921.

MLA (9th ed.) Citation

United States. Army. Air Corps. Report on Standard Test of A.C. Spark Plugs. U.S. GPO, 1921.

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