United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services: April 2016 : Information on Goods and Services, BEA 16-26, CB 16-97, FT-900 (16-04)," Bureau of Economic Analysis (BEA) News Releases (June 3, 2016). https://fraser.stlouisfed.org/title/6148/item/602346/content/pdf/bea_newsreleases_20160603_a_information-section, accessed on May 16, 2025.