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-. "September 15, 1971," G.12.3 Industrial Production (1971-09-15) : 3-3. https://fraser.stlouisfed.org/title/55/item/59792/toc/468232 , accessed on April 18, 2024.