Helgason, Guðmundur. "Ships hit during WWI: Southland (d.)". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "Ships hit by UB 14". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "Ships hit during WWI: Katja". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "Ships hit during WWI: Apscheron". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "Ships hit during WWI: E 20". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "WWI U-boats: UC 22". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "WWI U-boat commanders: Kurt Schwarz". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "WWI U-boat commanders: Ernst Ulrich". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "Ships hit during WWI: Karasunda". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.
Helgason, Guðmundur. "WWI U-boat commanders: Bodo Elleke". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 14 April 2009.