Source: US. Bureau of Labor Statistics
Release: U.S. Import and Export Price Indexes
For more information, please see the Import/Export Price Indexes web site at http://www.bls.gov/mxp
US. Bureau of Labor Statistics, Export (Harmonized System): Copper and articles thereof [ID74], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/ID74, July 26, 2016.