Burke, William and Levy, Yvonne. "Silver: End of an Era : From Surplus to Shortage," in Federal Reserve Bank of San Francisco. "November 1973 Supplement : Silver: End of an Era," Economic Review (Federal Reserve Bank of San Francisco) (November 1973) : 3-8. https://fraser.stlouisfed.org/title/869/item/520329/toc/513995 , accessed on April 24, 2024.