Board of Governors of the Federal Reserve System (U.S.), 1935-. "Market Groupings, Not Seasonally Adjusted," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "April 14, 1971," G.12.3 Industrial Production (1971-04-14) : 4-4. https://fraser.stlouisfed.org/title/55/item/59761/toc/468196 , accessed on May 11, 2024.