United States. Department of the Treasury. "Bill tender on monthly bills, March 24, 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) : 396-397. https://fraser.stlouisfed.org/title/6111/item/587011/toc/541717 , accessed on June 25, 2024.