Railroad Archives Online
- CollectionD0063 - Walter W. Ainsworth Collection
- Series004 - Northern Pacific Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3006 - Cabooses (Railroads)
- ItemWWANT044 - Northern Pacific freight train at Seattle, Washington, circa 1935.
- ItemWWANT049 - Northern Pacific freight train at Seattle, Washington, circa 1935.
- ItemWWANT079 - Northern Pacific freight train with a wood caboose at Black River, Washington, circa 1941.
- ItemWWANT089 - A Northern Pacific freight train at Black River, Washington, circa 1941.
- ItemWWANT091 - A Northern Pacific freight train at Black River, Washington, circa 1941.
- ItemWWANT093 - A Northern Pacific steam locomotive at Black River, Washington, circa 1941.