United States. Bureau of Economic Analysis. "May 1928," Survey of Current Business (May 1928). https://fraser.stlouisfed.org/title/46/item/9225, accessed on May 10, 2024.
United States. Bureau of Economic Analysis. "May 1928," Survey of Current Business (May 1928). https://fraser.stlouisfed.org/title/46/item/9225, accessed on May 10, 2024.