Railroad Archives Online
- CollectionD0504b - Al Christianson Collection - Friends of the Burlington Northern Railroad
- Series001 - Burlington Northern Railroad Company
- Subseries Level 1014 - Photographs
- Subseries Level 2001 - Railroads--Equipment and Supplies
- Subseries Level 3002 - Diesel Locomotives
- 406 more...
- ItemChristianson000486 - Burlington Northern Diesel Locomotive 6615 in 1981
- ItemChristianson000487 - Burlington Northern Diesel Locomotive 6621 at Minneapolis, Minnesota in 1981
- ItemChristianson000488 - Burlington Northern Diesel Locomotive 6621 at Saint Paul, Minnesota in 1980
- ItemChristianson000489 - Burlington Northern Diesel Locomotive 6621 at Saint Paul, Minnesota in 1980
- ItemChristianson000490 - Burlington Northern Diesel Locomotive 6624 at Staples, Minnesota in 1981
- ItemChristianson000491 - Burlington Northern Diesel Locomotive 6627 at Portland, Oregon in 1982
- ItemChristianson000492 - Burlington Northern Diesel Locomotive 6635 at Saint Paul, Minnesota in 1980
- ItemChristianson000493 - Burlington Northern Diesel Locomotive 6636 at Minneapolis, Minnesota in 1980
- ItemChristianson000494 - Burlington Northern Diesel Locomotive 6642 at Minneapolis, Minnesota in 1980
- 144 more...