TfL Corporate Design (January 2009). "3: Underground line colours". Line diagram standard(PDF) (3 ed.). Transport for London. Archived from the original(PDF) on 4 January 2022. Metropolitan line - Pantone 235, C:5 M:100 K:40
"Commissioner's Report"(PDF). Board Meeting Documents. Transport for London. 20 September 2012. paragraph 3.2. Archived(PDF) from the original on 26 August 2020. Retrieved 27 September 2012.
TfL Corporate Design (January 2009). "3: Underground line colours". Line diagram standard(PDF) (3 ed.). Transport for London. Archived from the original(PDF) on 4 January 2022. Metropolitan line - Pantone 235, C:5 M:100 K:40
"PPP Performance Report"(PDF). Transport for London. 2009–2010. pp. 7–8. Archived from the original(PDF) on 26 April 2012. Retrieved 7 March 2012.
"Commissioner's Report"(PDF). Board Meeting Documents. Transport for London. 20 September 2012. paragraph 3.2. Archived(PDF) from the original on 26 August 2020. Retrieved 27 September 2012.