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 1920," Federal Reserve Bulletin (July 1920) : 55-55. https://fraser.stlouisfed.org/title/62/item/20603/toc/102282 , accessed on May 8, 2024.