Board of Governors of the Federal Reserve System (U.S.), 1935-. "Explanatory Note," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "April 15, 1988," G.12.3 Industrial Production (1988-04-15) : 20-20. https://fraser.stlouisfed.org/title/55/item/59776/toc/474309 , accessed on May 2, 2024.