United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services, December 2009, BEA 10-04, CB 10-20, FT-900 (09-12)," Bureau of Economic Analysis (BEA) News Releases (February 10, 2010). https://fraser.stlouisfed.org/title/6148/item/601136, accessed on March 20, 2025.