Railroad Archives Online
- CollectionD0288 - Terence Wahl Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3001 - Steam Locomotives
- ItemTRWahl0007 - Northern Pacific Steam Locomotive 1507, Kelso, Washington, August 1951
- ItemTRWahl0008 - Northern Pacific Steam Locomotive 1690, Bellingham, Washington, October 1951
- ItemTRWahl0012 - Northern Pacific Steam Locomotive 1369, Bellingham, Washington, June-August 1952
- ItemTRWahl0013 - Northern Pacific Steam Locomotive 1361, Bellingham, Washington, undated
- ItemTRWahl0015 - Northern Pacific Steam Locomotive 1369, Bellingham, Washington, June-August 1952
- ItemTRWahl0017 - Northern Pacific Steam Locomotive 1369, Bellingham, Washington, June-August 1952
- ItemTRWahl0339 - Northern Pacific Steam Locomotive 1549, Bellingham, Washington, undated
- 89 more...