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49 (XLIX) — 1938-1939
U.S. Explosions, 280, 375.
U.S. Haulage Accidents, 340.
U.S. Lamp, Fuel, 101.
U.S. Minerals Year Book, 167.
U.S. Mines, Mechanisation, 281.
U.S. Record, Safety, 107.
Underground Accidents, 226.
Underground Boring, 383.
Underground Cables, 45, 365, 366.
Underground Fire Extinguisher, 346.
Underground Fires, 354, 377.
Underground Gasification of Coal, 244.
Underground Machinery, Choice, 164, 177, 201.
Upcast, Closing Top, 254.
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