Please specify if terms of license are complied with!ruhrpott2010 (2010-05-23). "Duisburg, die Hafenstadt im Pott". Ruhrpott2010's Blog.
Yuliya Georgieva (2014-08-10). From Rubble to the Ritz – Revitalizing Abandoned Sites (in en). landarchs.com. Retrieved on 2014-08-30.