Railroad Archives Online
- CollectionE0477 - BNSF Maps, Drawings and Records Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1009 - Engineering Records
- Subseries Level 2008 - Physical plant drawing
- Subseries Level 3008 - Tunnels
- ItemEBP0955 - Great Northern Technical Drawing, Cascade Tunnel, Washington, 1926
- ItemEBP0959 - Great Northern Technical Drawing, Cascade Tunnel, Washington, 1926
- ItemEBP0965 - Great Northern Technical Drawing, Cascade Tunnel, Washington, 1926
- ItemEBP0966 - Great Northern Technical Drawing, Cascade Tunnel, Washington, 1926
- ItemEBP4377 - Montana Central Railway Tunnel Technical Drawing, 1911