Sand and gravel excavation.

Author:	Thoenen, J. R.
Year:	1936
Document Type:	USBI
Issuing Agency:	U.S. Dept. of the Interior, Bureau of Mines,
SUDOC:	I 28.27:6879
Series:	Information circular / United States Department of the Interior, Bureau of Mines ;
Report Number:	6879
Subjects:	Sand
	Gravel
	Mining engineering
Link:	https://hdl.handle.net/2027/mdp.39015077569252