Railroad Archives Online
- CollectionD0153 - Doug Wingfield Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3005 - Maintenance of Way cars
- ItemWingfield.104 - Great Northern Snow Dozer X1688 at Spokane, Washington, 1968
- ItemWingfield.105 - Great Northern Snow Dozer X7303 at Bonners Ferry, Idaho, 1968
- ItemWingfield.106 - Great Northern Snow Dozer X7303 at Bonners Ferry, Idaho, 1968