United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services: May 2013 : Information Section, BEA 13-33, CB 13-122, FT-900 (13-05)," Bureau of Economic Analysis (BEA) News Releases (July 3, 2013). https://fraser.stlouisfed.org/title/6148/item/601556/content/pdf/bea_newsreleases_20130703_information-section, accessed on March 15, 2025.