Board of Governors of the Federal Reserve System (U.S.), 1935-. "Summary Groupings, Seasonally Adjusted," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "December 15, 1971," G.12.3 Industrial Production (1971-12-15) : 8-8. https://fraser.stlouisfed.org/title/55/item/59588/toc/468260 , accessed on March 29, 2024.