Railroad Archives Online
- ArkivD0288 - Terence Wahl Collection
- Serie004 - Northern Pacific Railroad Company
- Underserie014 - Photographs
- 001 - Railroads--Equipment and Supplies
- 006 - Cabooses (Railroads)
- ObjektTRWahl0009 - Northern Pacific Caboose 1276, Kelso, Washington, August 1951
- ObjektTRWahl0265 - Northern Pacific Caboose 1239, Arlington, Washington, undated
- ObjektTRWahl0485 - Northern Pacific Caboose 1294, Bellingham, Washington, undated
- ObjektTRWahl0832 - Northern Pacific Caboose, Bellingham, Washington, undated