1. Crimes Chicago—Data Portal: 〈https://data.cityofchicago.org/public-safety/crimes-2001-to-present/ijzp-q8t2〉
2. Crimes Philadelphia—Open Data: 〈http://www.opendataphilly.org/opendata/resource/215/philadelphia-police-part-one-crime-incidents〉
3. Openstreetmap: 〈http://www.openstreetmap.org〉
4. Osm Metro Extracts: 〈http://metro.teczno.com〉
5. osm4routing github: 〈https://github.com/tristramg/osm4routing〉