United States. Department of the Treasury. "U.S. Savings Bonds Issued and Redeemed Through April 30, 1973, May 14, 1973," in United States. Department of the Treasury. "Volume 184," Press Releases of the United States Department of the Treasury (April 27, 1973 - June 29, 1973) : 283-284. https://fraser.stlouisfed.org/title/6111/item/587027/toc/543223 , accessed on June 25, 2024.