Evaluation of structures for roof-fall areas /
by Richard A. Allwes and C.P. Mangelsdorf.
- Washington, D.C. : U.S. Dept. of the Interior, Bureau of Mines, [1992]
- 31 p. : ill. ; 28 cm.
- Report of investigations ; 9414 .
- Report of investigations (United States. Bureau of Mines) ; 9414. .