Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "Net Ton-Miles, Revenue and Nonrevenue," in Board of Governors of the Federal Reserve System (U.S.), 1935- and Federal Reserve Board, 1914-1935. "April 1921," Federal Reserve Bulletin (April 1921) : 90-90. https://fraser.stlouisfed.org/title/62/item/20522/toc/7106 , accessed on April 19, 2024.