United States. Bureau of Economic Analysis. "April 1968," Survey of Current Business (April 1968). https://fraser.stlouisfed.org/title/46/item/9752, accessed on April 14, 2024.
United States. Bureau of Economic Analysis. "April 1968," Survey of Current Business (April 1968). https://fraser.stlouisfed.org/title/46/item/9752, accessed on April 14, 2024.