United States. Department of the Treasury. "Lead and Zinc, June 11, 1964, Release Number d-1249," in United States. Department of the Treasury. "Volume 143," Press Releases of the United States Department of the Treasury (June 1, 1964 - July 31, 1964) : 81-83. https://fraser.stlouisfed.org/title/6111/item/586986/toc/539416 , accessed on June 24, 2024.