United States. Department of the Treasury. "Bill tender on 230-day tax bills, November 26, 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) : 349-350. https://fraser.stlouisfed.org/title/6111/item/587006/toc/541232 , accessed on June 23, 2024.