United States. Department of the Treasury. "Bill Offering, June 5, 1968, Release Number f-1268," in United States. Department of the Treasury. "Volume 162," Press Releases of the United States Department of the Treasury (June 5, 1968 - September 30, 1968) : 6-10. https://fraser.stlouisfed.org/title/6111/item/587005/toc/541072 , accessed on June 24, 2024.