@article{siegfried2020developing,
  title = {Developing a Sustainable Concept for Urban Last-Mile Delivery}
  author = {Siegfried, Patrick and Zhang, John Jiyuan},
  journal = {Open Journal of Business and Management},
  url = {http://www.scirp.org/Journal/Paperabs.aspx?paperid=106728},
  year = {2020}
}