Eider Canal (English Wikipedia)

Watty, Fred (2012). Kiel and the fjord region. Sutton Verlag GmbH. pp. 45–46. ISBN 9783954000616. Retrieved 29 October 2016.
Ward, Sir Adolphus William; Prothero, George Walter; Leathes, Sir Stanley Mordaunt; Benians, Ernest Alfred (1908). The Cambridge Modern History. Vol. 5. Macmillan. p. 580. Retrieved 29 October 2016.
Hansen, Christian (1860). The Great Holstein Ship-canal from Brunsbüttel to the Bay of Neustadt, for Uniting the Northsea and the Baltic. p. 6. Retrieved 29 October 2016.

britannica.com

"Geschichte des Eiderkanals". Canal-Verein e.V. (in German). Archived from the original on 16 July 2018.

"Geschichte des Eiderkanals". Canal-Verein e.V. (in German). Archived from the original on 16 July 2018.