Board of Governors of the Federal Reserve System (U.S.), 1935-. "Diffusion Indexes," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "December 14, 1987," G.12.3 Industrial Production (1987-12-14) : 15-15. https://fraser.stlouisfed.org/title/55/item/59726/toc/474225 , accessed on April 18, 2024.