United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services: March 2009, BEA 09-19, CB 09-73, FT-900 (09-03)," Bureau of Economic Analysis (BEA) News Releases (May 12, 2009). https://fraser.stlouisfed.org/title/6148/item/600669, accessed on June 25, 2025.