"Trial of coins." 15 members appointed by President Kennedy to take part in test at U.S. Mint in Philadelphia, Pennsylvania, February 6, 1961
United States. Department of the Treasury. ""Trial of coins." 15 members appointed by President Kennedy to take part in test at U.S. Mint in Philadelphia, Pennsylvania, February 6, 1961," in United States. Department of the Treasury. "Volume 124," Press Releases of the United States Department of the Treasury (January 24, 1961 - April 27, 1961) : 52-76. https://fraser.stlouisfed.org/title/6111/item/586967/toc/538386 , accessed on June 23, 2024.