Area of unsupported roof in coal mines :
conditions and factor[s] for consideration /
by J.W. Paul.

APA Citation

Paul, J. W. (James Washington). (1927). Area of unsupported roof in coal mines: conditions and factor[s] for consideration. Washington, D.C.: U.S. Dept. of Commerce, Bureau of Mines.

MLA Citation

Paul, J. W. (James Washington). Area of Unsupported Roof In Coal Mines: Conditions And Factor[s] for Consideration. Washington, D.C.: U.S. Dept. of Commerce, Bureau of Mines, 1927.

Warning: These citations may not always be complete (especially for serials).