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-. "September 18, 1972," G.12.3 Industrial Production (1972-09-18) : 8-8. https://fraser.stlouisfed.org/title/55/item/59566/toc/471370 , accessed on May 1, 2024.