Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "Index of Production of Minerals, by Products," in Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "August 1928," Federal Reserve Bulletin (August 1928) : 19-19. https://fraser.stlouisfed.org/title/62/item/20680/toc/175980 , accessed on April 25, 2024.