Perkins reports the date of the encounter as Sunday, 16 August 1915, but 16 August 1915 was actually a Monday. Messimer (p. 129), Gibson and Prendergast (pp. 50–51), and Uboat.net (Helgason, Guðmundur. "WWI U-boats: UB 4". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 19 February 2009.) all report the date of the encounter as 15 August 1915.
Helgason, Guðmundur. "WWI U-boats: UB 4". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 19 February 2009.
Helgason, Guðmundur. "WWI U-boat commanders: Karl Groß". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 5 March 2009.
Helgason, Guðmundur. "Ships hit during WWI: Harpalyce". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 5 March 2009.
Helgason, Guðmundur. "Ships hit by UB 4". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 5 March 2009.
Helgason, Guðmundur. "Ships hit during WWI: Ellispontos". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 5 March 2009.
Helgason, Guðmundur. "Ships hit during WWI: Bona Fide". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 5 March 2009.