Rujukan Masa_Bahagia_Pertama

  1. ↑ Purnell, Tom (April 11, 2003). "The "Happy Time"". "Canonesa", Convoy HX72 & U-100. Diarkibkan daripada yang asal pada October 1, 2007. Dicapai pada September 1, 2007.
  2. ↑ Blouet, Brian W. Global Geostrategy: Mackinder and the Defence of the West, p. 131
  3. ↑ Hughes, Terry; Costello, John. The Battle of the Atlantic, p. 88
  4. ↑ Macintyre, Donald G. F. W. The Naval War Against Hitler, p. 52
  5. ↑ Milner, Marc (June 2008). "The Battle That Had to Be Won". Naval History Magazine. United States Naval Institute. Dicapai pada 2017-03-09.

Templat:Germany-WWII-stub