Railroad Archives Online
- FondD0011 - James M. Fredrickson Collection
- Sorozat004 - Northern Pacific Railroad Company
- Alsorozat014 - Photographs
- 001 - Railroads--Equipment and Supplies
- 008 - Buses
- IratdarabJMF08-05409.0 - Northern Pacific Transport bus, number B41-20 at Tacoma, Washington, in 1960.
- IratdarabJMF08-05409.1 - Northern Pacific Transport bus, number B41-20 at Tacoma, Washington, in 1960.
- IratdarabJMF08-05415.0 - Northern Pacific Transport letter, July, 1956.
- IratdarabJMF08-05416.0 - Northern Pacific Transport bus, in 1956.
- IratdarabJMF08-05417.0 - Northern Pacific Transport bus, in 1956.
- IratdarabJMF08-05418.0 - Northern Pacific Transport bus, in 1956.
- IratdarabJMF08-05419.0 - Northern Pacific Transport bus, in 1956.