Railroad Archives Online
- CollectionE0045A - Great Northern Railway- Blueprint-Authorization for Expenditure Collection
- Series010 - Other Railroads
- Subseries Level 1009 - Engineering Records
- Subseries Level 2008 - Physical plant drawing
- Subseries Level 3008 - Tunnels
- ItemJSBP2166 - Great Northern Railway Historical Society Blueprint Collection JSBP2166, Hardy, Montana, 1918.
- ItemJSBP2167 - Great Northern Railway Historical Society Blueprint Collection JSBP2167, Hardy, Montana, 1918.