Railroad Archives Online
- CollectionD0036 - George Werkema Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3005 - Maintenance of Way cars
- 24 more...
- ItemWerkema291 - Northern Pacific open hopper car number 87742 at Denver, Colorado, in 1989.
- ItemWerkema292 - Northern Pacific hopper car number 87937 at Denver, Colorado, in 1981.
- ItemWerkema355 - Northern Pacific tank car 102007 at Pasco, Washington, in 1984.
- ItemWerkema356 - Northern Pacific tank car 102007 at Pasco, Washington, in 1984.
- ItemWerkema357 - Northern Pacific tank car 102040 at Denver, Colorado, in 1989.