Martin, William McChesney. Letter to John W. Snyder, Secretary of the Treasury, Box 11, Folder 4, William McChesney Martin, Jr., Papers. https://fraser.stlouisfed.org/archival/1341/item/456771, accessed on August 15, 2018.
Regarding change of interest rate.
- Board of Governors of the Federal Reserve System, Federal Reserve Board
- Meltzer's History of the Federal Reserve - Primary Sources