United States. Bureau of Mines. (1911). Miners' circular / United States Department of the Interior. Washington: Bureau of Mines; for sale by the Supt. of Docs., U.S. Govt. Print. Off..

United States. Bureau of Mines. Miners' Circular / United States Department of the Interior. Washington: Bureau of Mines; for sale by the Supt. of Docs., U.S. Govt. Print. Off., 1911.

United States. Bureau of Mines. Miners' Circular / United States Department of the Interior. Washington: Bureau of Mines; for sale by the Supt. of Docs., U.S. Govt. Print. Off., 1911.