Board of Governors of the Federal Reserve System (U.S.), 1935-. "Industry Groupings, Seasonally Adjusted," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "September 16, 1981," G.12.3 Industrial Production (1981-09-16) : 6-6. https://fraser.stlouisfed.org/title/55/item/59647/toc/472222 , accessed on March 28, 2024.