Knippschild, R. 2009. A waste of time and effort? Benefit and factors of success of cross-border cooperation in urban and regional development in the German-Polish-Czech triangle. Raumforschung und Raumordnung | Spatial Research and Planning. 67, 3 (May 2009), 228–238. DOI:https://doi.org/10.1007/BF03183008.