Technical Advances in Mining Make Available Low-Grade Ores, Offset Depletion, and Increase Output Per Worker : September 25, 1938, 4-1767
United States. Works Progress Administration. "Technical Advances in Mining Make Available Low-Grade Ores, Offset Depletion, and Increase Output Per Worker : September 25, 1938, 4-1767," Press Releases of the Works Progress Administration (September 25, 1938). https://fraser.stlouisfed.org/title/6753/item/619802, accessed on April 19, 2024.