Board of Governors of the Federal Reserve System (U.S.), 1935-. "Symbols and Abbreviations," in Board of Governors of the Federal Reserve System (U.S.), 1935-. "1992," Annual Statistical Digest (December 1993) : 4-4. https://fraser.stlouisfed.org/title/7/item/23498/toc/332823 , accessed on March 29, 2024.