Railroad Archives Online
- CollectionD0153 - Doug Wingfield Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3002 - Diesel Locomotives
- 30 more...
- ItemWingfield.206 - Northern Pacific Diesel Locomotive 2529, 868 at Spokane, Washington, 1968
- ItemWingfield.207 - Northern Pacific Diesel Locomotive 2529, 868 at Spokane, Washington, 1968
- ItemWingfield.208 - Northern Pacific Diesel Locomotive 2804, 2808, 2503 at Marshall, Washington, 1968
- ItemWingfield.209 - Northern Pacific Diesel Locomotive 2804, 2808, 2503 at Marshall, Washington, 1968
- ItemWingfield.210 - Northern Pacific Diesel Locomotive 2804, 2508, 2519 at Marshall, Washington, 1970
- ItemWingfield.189 - Northern Pacific Diesel Locomotive 3600, 2808, 2527 at Marshall, Washington, 1968
- ItemWingfield.191 - Northern Pacific Diesel Locomotive 3600, 2808, 2527 at Marshall, Washington, 1968
- ItemWingfield.193 - Northern Pacific Diesel Locomotive 3611, 7003d, 7003a at Marshall, Washington, 1968