Title: A study of lumber used for bracing trenches in the United States /
Authors: Knab, Lawrence I.; United States.
Publisher: U.S. Dept. of Commerce, National Bureau of Standards : for sale by the Supt. of Docs., U.S. Govt. Print. Off.,
Year: 1980
Subjects: Lumber.; Excavation Safety measures.; Shoring and underpinning.; Retaining walls Materials United States.; Excavation.