Railroad Archives Online
- CollectionD0036 - George Werkema Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3001 - Bridges
- Itemimg1167 - Great Northern Bridge at Karnak, North Dakota, 2003
- Itemimg1168 - Great Northern Bridge at Marysville, Washington, 1982
- Itemimg1169 - Great Northern Bridge at Marysville, Washington, 1982
- Itemimg1170 - Great Northern Bridge at Marysville, Washington, 1982
- Itemimg1171 - Great Northern Bridge at Marysville, Washington, 1982
- Itemimg1172 - Great Northern Bridge at Marysville, Washington, 1987
- Itemimg1173 - Great Northern Bridge at Marysville, Washington, 1987
- Itemimg1174 - Great Northern Bridge at Ferndale, Washington, 1966
- Itemimg1175 - Great Northern Bridge at Ferndale, Washington, 1966
- 20 more...