@article{chen2009material,
  title = {Material Flow and Circular Economy}
  author = {Chen, Jian Zhong},
  journal = {Systems Research and Behavioral Science},
  url = {http://www.springerlink.com/index/10.1007/s11213-010-9182-4%255Cnhttp://linkinghub.elsevier.com/retrieve/pii/S1475158504000025%255Cnhttp://informahealthcare.com/doi/abs/10.1080/13561820802168125%255Cnhttp://www.springerlink.com/index/10.1007/s11213-009-91},
  doi = {10.1002/sres.968},
  year = {2009}
}