Heidbrink, Ingo. “Petroleum Tanker Shipping on German Inland Waterways, 1887-1994”. The Northern Mariner / Le marin du nord 11, no. 2 (April 1, 2001): 57–67. Accessed November 23, 2024. https://tnm.journals.yorku.ca/index.php/default/article/view/590.