Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "Market Groupings, Seasonally Adjusted," in Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "September 1968," Federal Reserve Bulletin (September 1968) : 125-125. https://fraser.stlouisfed.org/title/62/item/21405/toc/65202 , accessed on March 28, 2024.