United States. Department of the Treasury. "Bill Tender on Monthly Bills, October 24, 1968," in United States. Department of the Treasury. "Volume 163," Press Releases of the United States Department of the Treasury (October 1, 1968 - January 20, 1969) : 149-150. https://fraser.stlouisfed.org/title/6111/item/587006/toc/541196 , accessed on June 23, 2024.