Railroad Archives Online
- CollectionD0036 - George Werkema Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2004 - Railroad tracks
- Subseries Level 3001 - Railroad mainline
- Itemimg1111 - Great Northern Track at Marysville, Washington, 1982
- Itemimg1112 - Great Northern Bumper Post at Leavenworth, Washington, 1987
- Itemimg1113 - Great Northern Track at Delta Junction, Washington, 1982
- Itemimg1114 - Great Northern Track at Tye, Washington, 1982
- Itemimg1115 - Great Northern Track at Tye, Washington, 1982