Technology, employment, and output per man: copper, iron, placer gold.
Published: 1937
Place of publication: [Philadelphia
Language: eng
Subjects: Gold mines and mining -- United States.; Iron mines and mining -- United States.; Copper mines and mining -- United States.; Miners -- United States.; Mining machinery.; Placer mining.
Notes: Reproduced from type-written copy.
"This volume contains WPA National research project reports nos. E-12, E-13, and E-2."