Railroad Archives Online
- CollectionD0036 - George Werkema Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2004 - Railroad Tracks
- Subseries Level 3003 - Railroad Yards
- ItemWerkema612 - Burlington Northern track tower at Portland, Oregon, in 1988.
- ItemWerkema613 - Burlington Northern terminal track machine at Portland, Oregon, in 1988.
- ItemWerkema614 - Burlington Northern terminal track machine at Portland, Oregon, in 1988.
- ItemWerkema615 - Burlington Northern yard office at Tacoma, Washington, in 1999.
- ItemWerkema616 - Burlington Northern yard office at Tacoma, Washington, in 1988.
- ItemWerkema635 - Northern Pacific yard at Laurel, Montana, in 1965.