United States. Department of the Treasury. "Lead and Zinc, February 14, 1964, Release Number d-1136," in United States. Department of the Treasury. "Volume 141," Press Releases of the United States Department of the Treasury (February 3, 1964 - March 30, 1964) : 85-87. https://fraser.stlouisfed.org/title/6111/item/586984/toc/539363 , accessed on June 23, 2024.