Source Information

• Tunnel data source information

  Primary source:

  Wolfram|Alpha Knowledgebase, 2024.

  Background sources and references:

  • Janberg, N. "Tunnels and Underground Structures." Structurae. »
  • Lotsberg, G. The World's Longest Tunnel Page. »
  • Robl, E. H. Longest Railroad Tunnels in the World. "http://www.robl.w1.com/Transport/tunnel.htm" (defunct)
  • The Wikimedia Foundation, Inc. Wikipedia. »

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