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References

  • Romero, Victor S. (June 2008). "San Francisco Tunnels: Past, Present and Future" (PDF). Tunnel Business Magazine. Peninsula, Ohio: Benjamin Media. pp. 14–17. ISSN  1553-2917. Retrieved 8 January 2018.
  • Nolte, Carl (2 November 2014). "Underground and underappreciated, tunnels' time has come". San Francisco Chronicle. Retrieved 12 December 2017.