Lüthi, Stefan, Alain Thierstein, and Michael Bentlage. 2011. “Interlocking Firm Networks in the German Knowledge Economy. On Local Networks and Global Connectivity”. Raumforschung Und Raumordnung | Spatial Research and Planning 69 (3): 161–174. https://doi.org/10.1007/s13147-011-0088-0.