Ahlers, Anna L. External, Max Planck Institute for the History of Science, Max Planck Society;
Ahlers, A. L. (2015). 鲁尔区《变回蓝天》对北京的启示 Lu'er qu <bian hui lantian> dui beijing de qishi (How the Sky over the Ruhr Became Blue Again: A Vision for Beijing). 小康 Xiaokang (Insight China), (23).