Board of Governors of the Federal Reserve System (U.S.), 1935-. "Industry Groupings, Seasonally Adjusted," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "April 16, 1969," G.12.3 Industrial Production (1969-04-16) : 3-3. https://fraser.stlouisfed.org/title/55/item/59592/toc/465868 , accessed on April 18, 2024.