Helgason، Guðmundur. "WWI U-boats: UB 8". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2009-03-02.
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Helgason، Guðmundur. "WWI U-boats: UB 3". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-02-10.
Helgason، Guðmundur. "WWI U-boats: UB 4". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2009-03-02.
Helgason، Guðmundur. "WWI U-boats: UB 5". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-02-10.
Helgason، Guðmundur. "WWI U-boats: UB 6". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-02-10.
Helgason، Guðmundur. "WWI U-boats: UB 7". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-02-10.
Helgason، Guðmundur. "WWI U-boats: UB 9". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2009-03-02.
Helgason، Guðmundur. "WWI U-boats: UB 10". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2009-03-02.
Helgason، Guðmundur. "WWI U-boats: UB 11". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: UB 12". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: UB 13". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: UB 14". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2009-03-02.
Helgason، Guðmundur. "WWI U-boats: UB 16". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: UB 17". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: KUK U 15". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: KUK U 16". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.
Helgason، Guðmundur. "WWI U-boats: KUK U 17". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. اطلع عليه بتاريخ 2010-04-18.