Eichhorn, Sebastian, and Stefan Siedentop. “Inside before Outside? An Estimate of Inner Urban Development in North Rhine-Westphalian Municipalities, 1979 to 2011”. Raumforschung und Raumordnung | Spatial Research and Planning 80, no. 6 (December 30, 2022): 640–658. Accessed April 30, 2024. https://rur.oekom.de/index.php/rur/article/view/178.