Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "Group Index Numbers - United States, Bureau of Labor Statistics," in Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "July 1921," Federal Reserve Bulletin (July 1921) : 80-80. https://fraser.stlouisfed.org/title/62/item/20525/toc/306684 , accessed on May 13, 2024.