Transport for London. «El metro al 2010 (anglès)», 2006. Arxivat de l'original el 2011-07-15. [Consulta: 3 novembre 2007]. (map illustrating future development phases as proposed by TfL in 2006, subject to change)
tfl.gov.uk
Transport for London. «El metro al 2010 (anglès)», 2006. Arxivat de l'original el 2011-07-15. [Consulta: 3 novembre 2007]. (map illustrating future development phases as proposed by TfL in 2006, subject to change)