Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "Group Index Numbers-Spain-Institute of Geography and Statistics," in Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "May 1923," Federal Reserve Bulletin (May 1923) : 71-71. https://fraser.stlouisfed.org/title/62/item/20548/toc/370073 , accessed on April 19, 2024.