United States. Department of the Treasury. "Option exchange offering of 3 3/8% and 3 1/2%, January 31, 1957," in United States. Department of the Treasury. "Volume 109," Press Releases of the United States Department of the Treasury (January 3, 1957 - April 30, 1957) : 92-96. https://fraser.stlouisfed.org/title/6111/item/586952/toc/537291 , accessed on June 25, 2024.