Railroad Archives Online
- CollectionD0036 - George Werkema Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3005 - Signals and Signs
- ItemWerkema574 - Northern Pacific semaphore signal display at Chehalis, Washington, in 1988.
- ItemWerkema575 - Burlington Northern station order board signal at Connell, Washington, in 1987.
- ItemWerkema576 - Burlington Northern station order board signal at Connell, Washington, in 1987.
- ItemWerkema577 - Burlington Northern semaphore signals at Eltopia, Washington, in 1986.
- ItemWerkema578 - Burlington Northern semaphore signals at Gibbon, Washington, in 1986.
- ItemWerkema579 - Burlington Northern semaphore signals at Glade, Washington, in 1986.
- ItemWerkema580 - Burlington Northern signal bridge at Pasco, Washington, in 1986.
- ItemWerkema581 - Burlington Northern signal bridge at Pasco, Washington, in 1986.
- 8 more...