United States. Department of the Treasury. "Sale of U.S. Savings Stamps to be discontinued, February 2, 1970," in United States. Department of the Treasury. "Volume 168," Press Releases of the United States Department of the Treasury (February 2, 1970 - April 30, 1970) : 3-10. https://fraser.stlouisfed.org/title/6111/item/587011/toc/541657 , accessed on June 25, 2024.