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-. "June 15, 1988," G.12.3 Industrial Production (1988-06-15) : 14-14. https://fraser.stlouisfed.org/title/55/item/59736/toc/474348 , accessed on April 30, 2024.