APA (7th ed.) Citation

United States. Bureau of Mines. (1940). Cooling mine air during summer months to prevent roof falls. [s.n.].

Chicago Style (17th ed.) Citation

United States. Bureau of Mines. Cooling Mine Air During Summer Months to Prevent Roof Falls. [Washington]: [s.n.], 1940.

MLA (9th ed.) Citation

United States. Bureau of Mines. Cooling Mine Air During Summer Months to Prevent Roof Falls. [s.n.], 1940.