Some information on timbering bituminous-coal mines /

"Much of the material in this circular was taken from Miners' circular 31 [Questions and answers on timbering bituminous coal mines] prepared by J.W. Paul and published in January 1928."--P. 1.At head of title: ... United States Department of the Interior. Harold L. Ickes, secretary. Bureau of Mines. John W. Finch, director.Mode of access: Internet

Use of the miners' self-rescuer /

At head of title: ... Department of Commerce. Herbert Hoover, secretary. Bureau of Mines. Scott Turner, director.Mode of access: Internet