United States. Department of the Treasury. "Lead and Zinc, October 11, 1963, Release Number d-1001," in United States. Department of the Treasury. "Volume 139," Press Releases of the United States Department of the Treasury (October 1, 1963 - November 28, 1963) : 134-137. https://fraser.stlouisfed.org/title/6111/item/586982/toc/539289 , accessed on June 23, 2024.