Railroad Archives Online
- FondoD0063 - Walter W. Ainsworth Collection
- Serie004 - Northern Pacific Railroad Company
- Sottoserie014 - Photographs
- 001 - Railroads--Equipment and Supplies
- 002 - Diesel Locomotives
- Unità documentariaWWANT305 - Northern Pacific diesel locomotive number 6506 at Allentown, Washington, circa 1948.
- Unità documentariaWWASPSL4-082 - Northern Pacific Diesel Locomotive 7014A, Washington State, undated