United States. Department of the Treasury. "Bill Tender, September 12, 1966, Release Number f-612," in United States. Department of the Treasury. "Volume 155," Press Releases of the United States Department of the Treasury (August 1, 1966 - October 31, 1966) : 267-268. https://fraser.stlouisfed.org/title/6111/item/586998/toc/540272 , accessed on June 23, 2024.