@article{guo2017comparative,
  title = {Comparative assessment of circular economy development in China’s four megacities: The case of Beijing, Chongqing, Shanghai and Urumqi}
  author = {Guo, Bin; Geng, Yong; Ren, Jingzheng; Zhu, Lei; Liu, Yaxuan; Sterr, Thomas},
  journal = {Journal of Cleaner Production},
  url = {http://www.sciencedirect.com/science/article/pii/S0959652617312313},
  doi = {10.1016/j.jclepro.2017.06.061},
  year = {2017}
}