Railroad Archives Online
- CollectionD0288 - Terence Wahl Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3007 - Tunnels
- ItemTRWahl0156 - Great Northern Tunnel Tunnel, East Portal, Washington, undated
- ItemTRWahl0130 - Great Northern Tunnel, Scenic, Washington, undated
- ItemTRWahl0886 - Great Northern Tunnel, Scenic, Washington, undated