Railroad Archives Online
- FondsD0036 - George Werkema Collection
- Serie003 - Great Northern Railway Company (U.S.)
- Teilserie014 - Photographs
- 003 - Railroads--Buildings and Structures
- 007 - Tunnels
- Objektimg1117 - Great Northern Tunnel at Scenic, Washington, 1999
- Objektimg1120 - Great Northern Tunnel at Scenic, Washington, 1982
- Objektimg1121 - Great Northern Tunnel at Berne, Washington, 1982
- Objektimg1122 - Great Northern Tunnel at Berne, Washington, 1982
- Objektimg1123 - Great Northern Tunnel at Berne, Washington, 1982
- 5 mehr...