United States. Department of the Treasury. "Bill Tender, September 11, 1967, Release Number f-1022," in United States. Department of the Treasury. "Volume 159," Press Releases of the United States Department of the Treasury (September 1, 1967 - November 29, 1967) : 36-40. https://fraser.stlouisfed.org/title/6111/item/587002/toc/540639 , accessed on May 6, 2024.