United States. Bureau of Mines. (1937). Liquid carbon dioxide used to extinguish gob fire in German coal mine. [s.n.].
Chicago Style (17th ed.) CitationUnited States. Bureau of Mines. Liquid Carbon Dioxide Used to Extinguish Gob Fire in German Coal Mine. [Washington]: [s.n.], 1937.
MLA (9th ed.) CitationUnited States. Bureau of Mines. Liquid Carbon Dioxide Used to Extinguish Gob Fire in German Coal Mine. [s.n.], 1937.
Warning: These citations may not always be 100% accurate.