United States. Department of the Treasury. "Regional filing of tax returns, March 31, 1965, Release Number d-1555," in United States. Department of the Treasury. "Volume 147," Press Releases of the United States Department of the Treasury (February 1, 1965 - March 31, 1965) : 803-805. https://fraser.stlouisfed.org/title/6111/item/586990/toc/539720 , accessed on June 24, 2024.