"ON convoys". Andrew Hague Convoy Database. Retrieved 19 June 2011.
"SC convoys". Andrew Hague Convoy Database. Retrieved 19 June 2011.
"HX convoys". Andrew Hague Convoy Database. Retrieved 19 June 2011.
jstor.org
Frank Freidel, "FDR vs. Hitler: American Foreign Policy, 1933–1941" Proceedings of the Massachusetts Historical Society Vol. 99 (1987), pp. 25–43 online p. 39