Board of Governors of the Federal Reserve System (U.S.), 1935-. "Industry Groupings, Seasonally Adjusted and Unadjusted," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "December 15, 1971," G.12.3 Industrial Production (1971-12-15) : 3-3. https://fraser.stlouisfed.org/title/55/item/59588/toc/468264 , accessed on May 1, 2024.