Burgess, George W. Letter to Richard N. Johnson, Box 13, Folder 4, William McChesney Martin, Jr., Papers. https://fraser.stlouisfed.org/archival/1341/item/456895, accessed on August 14, 2018.
Regarding estimates for American-flag and foreign-flag airlines
- Board of Governors of the Federal Reserve System, Federal Reserve Board
- Meltzer's History of the Federal Reserve - Primary Sources