Helgason, Guðmundur. "WWI U-boats: U 73". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "WWI U-boat commanders: Gustav Sieß". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "WWI U-boat commanders: Ernst von Voigt". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "WWI U-boat commanders: Karl Meusel". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "WWI U-boat commanders: Carl Bünte". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "WWI U-boat commanders: Fritz Saupe". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "Ships hit during WWI: Britannic". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.
Helgason, Guðmundur. "Ships hit by U 73". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 24 December 2014.