Board of Governors of the Federal Reserve System (U.S.), 1935-. "Treasury Currency and SDR Certificates, Unadjusted Net Flows," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "September 30, 1988 : Annual Revisions," Z.1 Financial Accounts of the United States (1988-09-30) : 37-37. https://fraser.stlouisfed.org/title/93/item/69039/toc/484266 , accessed on March 28, 2024.