Railroad Archives Online
- CollectionD0173A - Hal Will Collection
- Series003 - Great Northern Railway Company (U.S.)
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3002 - Diesel Locomotives
- ItemMOHAI.90.24.04 - Great Northern Diesel Locomotive 503 Leading a Passenger Train at Interbay, Washington in 1947.
- ItemMOHAI.90.24.04.crop - Great Northern Diesel Locomotive 503 Leading a Passenger Train at Interbay, Washington in 1947.
- ItemMOHAI.90.24.05 - Great Northern Diesel Locomotive 504 leading a Passenger Train at Interbay, Washington in 1947.
- ItemMOHAI.90.24.10 - Great Northern Diesel Locomotive 511 leading a Passenger Train at Interbay, Washington in 1947.
- ItemMOHAI.90.24.22 - Great Northern Diesel Locomotive 511 with Steam Locomotives at Interbay, Washington Roundhouse in 1947.