United States. Department of the Treasury. "U.S. Savings Bonds Issued and Redeemed through April 30, 1969, May 8, 1969," in United States. Department of the Treasury. "Volume 165," Press Releases of the United States Department of the Treasury (May 6, 1969 - August 29, 1969) : 23-24. https://fraser.stlouisfed.org/title/6111/item/587008/toc/541417 , accessed on June 22, 2024.