Board of Governors of the Federal Reserve System (U.S.), 1935-. "Summary Groupings, Quarterly," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "Industrial Production Indexes 1979," G.12.3 Industrial Production (1980-09-01) : 12-12. https://fraser.stlouisfed.org/title/55/item/59635/toc/492543 , accessed on April 19, 2024.