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-. "March 17, 1981," G.12.3 Industrial Production (1981-03-17) : 15-15. https://fraser.stlouisfed.org/title/55/item/59642/toc/472156 , accessed on April 18, 2024.