Alecke, Björn, Gerhard Untiedt, Martin Gornig, Wolfgang Jaedicke, Matthias Koziol, and Jörg Walther. 2008. “Investment and Promotion Requirements of Urban Development 2007 until 2013 in Germany”. Raumforschung Und Raumordnung | Spatial Research and Planning 66 (3): 282–289. https://doi.org/10.1007/BF03183163.