United States. Department of the Treasury. "U.S. Savings Bonds Issued and Redeemed Through June 30, 1973, July 18, 1973," in United States. Department of the Treasury. "Volume 185," Press Releases of the United States Department of the Treasury (July 2, 1973 - August 31, 1973) : 214-222. https://fraser.stlouisfed.org/title/6111/item/587028/toc/543328 , accessed on June 28, 2024.