Greiving, Stefan, Florian Flex, and Thomas Terfrüchte. 2015. “Comparative Study on the Central Place Concepts of the GermanLänder and Recommendations for Their Further Development”. Raumforschung Und Raumordnung | Spatial Research and Planning 73 (4): 285–297. https://doi.org/10.1007/s13147-015-0357-4.