Helgason, Guðmundur. "WWI U-boat commanders: Otto Ehrentraut". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 23 February 2015.
Helgason, Guðmundur. "Ships hit by UC 39". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 23 February 2015.