@article{maud2021cities,
  title = {Cities as organisms: Urban metabolism of the four main Danish cities}
  author = {Maud Lanau, Ruichang Mao, Gang Liu},
  journal = {Cities},
  url = {https://www.sciencedirect.com/science/article/abs/pii/S0264275121002365},
  doi = {10.1016/j.cities.2021.103336},
  year = {2021}
}