United States. Department of Commerce. "U.S. International Trade in Goods and Services: June 2015, BEA 15-37, CB 15-135, FT-900 (15-06),"
United States Department of Commerce News
(August 5, 2015).
https://fraser.stlouisfed.org/title/6148/item/602255, accessed on May 30, 2026.