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
- ItemWingfield.148 - Northern Pacific Diesel Locomotive 803 at Duluth, Minnesota, 1961
- ItemWingfield.149 - Northern Pacific Diesel Locomotive 404, 410 at Spokane, Washington, 1968
- ItemWingfield.168 - Northern Pacific Diesel Locomotive 7006D at Spokane, Washington, 1968
- ItemWingfield.169 - Northern Pacific Diesel Locomotive 7009A at Spokane, Washington, 1968
- ItemWingfield.170 - Northern Pacific Diesel Locomotive 7009A at Spokane, Washington, 1968
- ItemWingfield.171 - Northern Pacific Diesel Locomotive 6503B at Seattle, Washington, 1962
- ItemWingfield.172 - Northern Pacific Diesel Locomotive 6506C, 6503B, 6503C at Seattle, Washington, 1962
- 31 more...