D. Guth, C. . Holz-Rau, M. Maciolek, and J. Scheiner, “Employment Suburbanisation, Urban Spatial Structure and Commuter Traffic: Trends in German Metropolitan Areas 1999-2007”, RuR, vol. 68, no. 4, pp. 283–295, Aug. 2010, doi: 10.1007/s13147-010-0026-6.