United States. Department of the Treasury. "Lead and Zinc, September 13, 1963, Release Number d-969," in United States. Department of the Treasury. "Volume 138," Press Releases of the United States Department of the Treasury (August 2, 1963 - September 25, 1963) : 274-276. https://fraser.stlouisfed.org/title/6111/item/586981/toc/539257 , accessed on June 24, 2024.