United States. Bureau of Economic Analysis. "March 1968," Survey of Current Business (March 1968). https://fraser.stlouisfed.org/title/46/item/9751, accessed on April 17, 2024.
United States. Bureau of Economic Analysis. "March 1968," Survey of Current Business (March 1968). https://fraser.stlouisfed.org/title/46/item/9751, accessed on April 17, 2024.