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 Year: 1940
 Collection: Government Documents A to Z Digitization Project
 Collection: World War Two Collection
Theory of ballooning.
A general guide to piloting a free balloon. digital.library.unt.edu/ark:/67531/metadc9808/
Lathes
A guide to the operation and maintenance of lathes for general shop work. digital.library.unt.edu/ark:/67531/metadc96655/
Grinding machines
This report provides the definition of grinding and discusses different processes, types, and operations of grinding. digital.library.unt.edu/ark:/67531/metadc96656/