"Ruhr Occupation". Encyclopedia Britannica. 14 April 2009. Archived from the original on 14 April 2023. Retrieved 14 April 2023.
dhm.de
Wulfert, Anja (22 January 2002). "Der Märzaufstand 1920" [The March Uprising 1920]. Deutsches Historisches Museum (in German). Archived from the original on 14 April 2023. Retrieved 14 April 2023.
Christian Berndt, "Ruhr Firms between Dynamic Change and Structural Persistence. Globalization, the 'German Model' and Regional Place-Dependence", Transactions of the Institute of British Geographers New Series, Vol. 23, No. 3 (1998), pp. 331–352 in JSTORArchived 26 October 2016 at the Wayback Machine
Ruhr, Regionalverband (9 January 2018). "Zensus 2011" (in German). www.metropoleruhr.de. Archived from the original on 6 February 2018. Retrieved 5 February 2018.
Ruhr, Regionalverband (28 September 2017). "Studierende". www.metropoleruhr.de (in German). Archived from the original on 7 October 2017. Retrieved 2 October 2017.
Ruhr, Regionalverband (9 January 2018). "Zensus 2011" (in German). www.metropoleruhr.de. Archived from the original on 6 February 2018. Retrieved 5 February 2018.
Wulfert, Anja (22 January 2002). "Der Märzaufstand 1920" [The March Uprising 1920]. Deutsches Historisches Museum (in German). Archived from the original on 14 April 2023. Retrieved 14 April 2023.
"Ruhr Occupation". Encyclopedia Britannica. 14 April 2009. Archived from the original on 14 April 2023. Retrieved 14 April 2023.
Christian Berndt, "Ruhr Firms between Dynamic Change and Structural Persistence. Globalization, the 'German Model' and Regional Place-Dependence", Transactions of the Institute of British Geographers New Series, Vol. 23, No. 3 (1998), pp. 331–352 in JSTORArchived 26 October 2016 at the Wayback Machine
Ruhr, Regionalverband (28 September 2017). "Studierende". www.metropoleruhr.de (in German). Archived from the original on 7 October 2017. Retrieved 2 October 2017.