Helgason, Guðmundur. WWI U-boat commanders: Willy Stüben. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2021-03-02].
Helgason, Guðmundur. WWI Officer Crews: Crew 4/07. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-04].
Helgason, Guðmundur. Ships hit during WWI: Katwijk. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit by UB 10. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-30].
Helgason, Guðmundur. Ships hit during WWI: Menapier. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Helgason, Guðmundur. Ships hit during WWI: Ships hit during WWI: Achieve. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Athena. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Coriander. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Fitzgerald. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Prospector. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Quest. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Strive. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Venture. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net.. U-Boat War in World War I. Uboat.net. Retrieved 2009-03-31.
Helgason, Guðmundur. Ships hit during WWI: Alert. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Fulgens. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Arbor Vitae. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Xmas Rose. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Rosalie. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Helgason, Guðmundur. Ships hit during WWI: Ships hit during WWI: Esperance. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: George Borrow. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: George Crabbe. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Humphrey. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Illustrious. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Oceans Gift. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Palm. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Trevear. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Welcome. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net., Helgason, Guðmundur. Ships hit during WWI: Young Admiral. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net.. U-Boat War in World War I. Uboat.net. Retrieved 2009-03-31.
Helgason, Guðmundur. Ships hit during WWI: Belford. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Huntly. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Port Dalhousie. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Peter Hanre. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: HMS Lassoo. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Helgason, Guðmundur. Ships hit during WWI: Amstelstromm. German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. [2009-03-31].
Karau,第48頁. Karau, Mark D. Wielding the Dagger: the MarineKorps Flandern and the German War Effort, 1914–1918. Westport, Connecticut: Praeger Publishing. 2003. ISBN 978-0-313-32475-8. OCLC 51204317.
Karau,第49頁. Karau, Mark D. Wielding the Dagger: the MarineKorps Flandern and the German War Effort, 1914–1918. Westport, Connecticut: Praeger Publishing. 2003. ISBN 978-0-313-32475-8. OCLC 51204317.
Karau,第50頁. Karau, Mark D. Wielding the Dagger: the MarineKorps Flandern and the German War Effort, 1914–1918. Westport, Connecticut: Praeger Publishing. 2003. ISBN 978-0-313-32475-8. OCLC 51204317.
Karau,第51頁. Karau, Mark D. Wielding the Dagger: the MarineKorps Flandern and the German War Effort, 1914–1918. Westport, Connecticut: Praeger Publishing. 2003. ISBN 978-0-313-32475-8. OCLC 51204317.
Karau,第221頁. Karau, Mark D. Wielding the Dagger: the MarineKorps Flandern and the German War Effort, 1914–1918. Westport, Connecticut: Praeger Publishing. 2003. ISBN 978-0-313-32475-8. OCLC 51204317.