Railroad Archives Online
- CollectionD0504b - Al Christianson Collection - Friends of the Burlington Northern Railroad
- Series001 - Burlington Northern Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2003 - Railroads--Buildings and Structures
- Subseries Level 3001 - Railroad bridges(Draft)
- ItemChristianson000001 - Burlington Northern Eastbound Coal Train in Valley City, North Dakota in 1981
- ItemChristianson000002 - Burlington Northern Westbound Grain Train in Minot, North Dakota in 1981
- ItemChristianson000003 - Burlington Northern Westbound Grain Train in Minot, North Dakota in 1981
- ItemChristianson000004 - Burlington Northern Westbound intermodal Train in Minneapolis, Minnesota in 1980
- ItemChristianson000005 - Burlington Northern Eastbound Coal Train in Valley City, North Dakota in 1981
- ItemChristianson000007 - Burlington Northern Westbound Empty Coal Train in Valley City, North Dakota in 1981