1. Accession, 2006. Helping make places more accessible. Available from 〈http://www.accessiongis.com/〉.
2. Mapping for wheelchair users: route navigation in urban spaces;Beale;The Cartographic Journal,2006
3. Spon's Civil Engineering and Highway Works Price Book,2008
4. Department of the Environment, Transport and the Regions, 2003a. National Travel Survey, 1998–2000 [computer file], second ed. UK Data Archive [distributor], Colchester, Essex, February 2003, SN: 4584.
5. Department of the Environment, Transport and the Regions, 2003b. National Travel Survey, 1999–2001 [computer file], second ed. UK Data Archive [distributor], Colchester, Essex, February 2003, SN: 4585.