REMOVE

1. Coal
2. Douglas, T.
3. 1910s

WHAT

1. GMO (1)
2. Operations (1)
3. Steam (1)
4. Structures (1)

WHERE

1. Cobre (1)

WHO

1. Boese, P.R. (1)
2. Cannon, L.G. (1)
3. Davidson, H.A. (1)
4. Duddleson, T.J. (1)