@misc{indiciae3534065470c1,
  title = {Congestion charging and the walking classes.},
  author = {Ian Roberts},
  year = {2003},
  doi = {10.1136/bmj.326.7385.345},
  url = {https://pubmed.ncbi.nlm.nih.gov/12586642/},
  note = {Source identifier: 12586642}
}