Railroad Archives Online
- CollectionD0173A - Hal Will Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3002 - Diesel Locomotives
- ItemMOHAI.90.24.63 - Northern Pacific Diesel Locomotive at Seattle, Washington in 1955.
- ItemMOHAI.90.24.65 - Northern Pacific Diesel Locomotive at Seattle, Washington in 1955.