Industry Division - Mining
United States. Bureau of Employment Security. "Industry Division - Mining," in United States. Bureau of Employment Security. "Employment Security Memorandum, No. 6," Employment and Pay Rolls in State Unemployment Compensation Systems, 1938 (1938) : 8-12. https://fraser.stlouisfed.org/title/193/item/5442/content/pdf/emppay_esm_194040v2/toc/122086 , accessed on April 17, 2024.