United States. Bureau of Labor Statistics. "Producer Price Indexes for Special Commodity Groupings," in United States. Bureau of Labor Statistics. "March 2010 (Corrected)," PPI Detailed Report (March 2010 (Corrected)) : 162-163. https://fraser.stlouisfed.org/title/63/item/21893/toc/116400 , accessed on April 19, 2024.