United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services: Annual Revision for 2015, BEA 15-24, CB 15-95, FT-900 (15-04)," Bureau of Economic Analysis (BEA) News Releases (June 3, 2015). https://fraser.stlouisfed.org/title/6148/item/602242, accessed on March 28, 2025.