Board of Governors of the Federal Reserve System (U.S.), 1935-. "Indexes, Quarterly Averages," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "1987 Revision," G.12.3 Industrial Production (1987-01-01) : 23-23. https://fraser.stlouisfed.org/title/55/item/59714/toc/492579 , accessed on April 25, 2024.