United States. Department of the Treasury. "National Savings Bonds Director, March 14, 1969," in United States. Department of the Treasury. "Volume 164," Press Releases of the United States Department of the Treasury (January 22, 1969 - April 30, 1969) : 134-136. https://fraser.stlouisfed.org/title/6111/item/587007/toc/541346 , accessed on June 24, 2024.