http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
https://www.ordnancesurvey.co.uk/business-and-government/licensing/licences/os-openspace-developer-agreement.html
http://www.openstreetmap.org/copyright
http://opendatacommons.org/licenses/odbl/
http://www.microsoft.com/maps/product/terms.html
http://wiki.openstreetmap.org/wiki/File:Bing_license.pdf