Would a Victoria line extension into South London along with the

Victoria line - Wikipedia

What Might Have Been At Walthamstow And Woodford

London Underground Major Regeneration Scheme - Railway Technology

Why are there so few tube lines in south London? - City Monitor

A Brief History of the Northern Line - Londontopia

London Underground, Overground, DLR, Tramlink and National Rail Services in BNS : r/TransitDiagrams

Proposal to extend the Northern line to Clapham Junction

The 50th anniversary of the Victoria line extension to Brixton

London Underground, Overground, DLR, Tramlink and National Rail Services in BNS : r/TransitDiagrams

The Northern Line, Page 10

London Victoria and South London resignalling programme - Network Rail