United States. Bureau of Economic Analysis. "U.S. International Trade in Goods and Services: December 2015 : Information on Goods and Services, BEA 16-06, CB 16-20, FT-900 (15-12),"
Bureau of Economic Analysis (BEA) News Releases
(February 5, 2016).
https://fraser.stlouisfed.org/title/6148/item/602325/content/pdf/bea_newsreleases_20160205_information-section, accessed on March 8, 2025.