1.
Schlürmann J. Jan Rüger: Heligoland. Britain, Germany, and the Struggle for the North Sea. Oxford University Press, 2017. HT [Internet]. 21. august 2019 [henvist 22. september 2021];118(2):118:2, 559-562. Tilgængelig hos: https://tidsskrift.dk/historisktidsskrift/article/view/115526