APA (7th ed.) Citation

United States. War Department. (1920). Index to numbered circulars, War Department, 1920-1932, both years inclusive. U.S. GPO.

Chicago Style (17th ed.) Citation

United States. War Department. Index to Numbered Circulars, War Department, 1920-1932, Both Years Inclusive. Washington: U.S. GPO, 1920.

MLA (9th ed.) Citation

United States. War Department. Index to Numbered Circulars, War Department, 1920-1932, Both Years Inclusive. U.S. GPO, 1920.