Board of Governors of the Federal Reserve System (U.S.), 1935-. "Gross public debt of the U.S. Treasury-Types and ownership," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "1987," Annual Statistical Digest (October 1988) : 97-97. https://fraser.stlouisfed.org/title/7/item/23493/toc/193455 , accessed on April 24, 2024.