United States. Department of the Treasury. "U.S. Savings bonds issued and Redeemed through May 31, 1970, June 8, 1970," in United States. Department of the Treasury. "Volume 169," Press Releases of the United States Department of the Treasury (May 6, 1970 - August 3, 1970) : 313-314. https://fraser.stlouisfed.org/title/6111/item/587012/toc/541798 , accessed on June 16, 2024.