United States. Department of Commerce and United States. Bureau of Economic Analysis. "Fourth Quarter 1956," The National Income and Product Account (1957-04-01). https://fraser.stlouisfed.org/title/52/item/57459, accessed on April 26, 2024.
United States. Department of Commerce and United States. Bureau of Economic Analysis. "Fourth Quarter 1956," The National Income and Product Account (1957-04-01). https://fraser.stlouisfed.org/title/52/item/57459, accessed on April 26, 2024.