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 3003 - Freight Cars
- 172 more...
- ItemWerkema303 - Northern Pacific hopper car number 72136 at Albuquerque, New Mexico, in 1979.
- ItemWerkema304 - Northern Pacific hopper car number 72136 at Albuquerque, New Mexico, in 1981.
- ItemWerkema305 - Northern Pacific hopper car number 72136 at Albuquerque, New Mexico, in 1980.
- ItemWerkema306 - Northern Pacific hopper car number 73006 at Longmont, Colorado, in 1980.
- ItemWerkema307 - Northern Pacific hopper car number 73086 at Longmont, Colorado, in 1985.
- ItemWerkema308 - Northern Pacific hopper car number 75208 at Idaho Falls, Idaho, in 1981.
- ItemWerkema309 - Northern Pacific hopper car number 75219 at Amarillo, Texas, in 1980.
- ItemWerkema310 - Northern Pacific hopper car number 75243 at Denver, Colorado, in 1976.
- ItemWerkema311 - Northern Pacific hopper car number 75271 at Denver, Colorado, in 1965.
- 42 more...