Rink, Dieter, and Manuel Wolff. “Housing Vacancy in Germany. On the Conceptualization of a Key Indicator for Housing Monitoring by Using Data from the German Housing Census (GWZ) 2011”. Raumforschung Und Raumordnung | Spatial Research and Planning, vol. 73, no. 5, Oct. 2015, pp. 311–325, https://doi.org/10.1007/s13147-015-0361-8.