Railroad Archives Online
- FondosE0477 - BNSF Maps, Drawings and Records Collection
- Series003 - Great Northern Railway Company (U.S.)
- Sub-series009 - Engineering Records
- 005 - Signals
- ItemEBP0437 - Signals Technical Drawing, 1901
- ItemEBP1860 - Great Northern Track Technical Drawing, 1907
- ItemEBP2618 - Northern Pacific Signal Technical Drawing, 1902
- ItemEBP3610 - Northern Pacific Signal Technical Drawing, 1898
- ItemEBP4365 - Great Northern Signal Technical Drawing, 1912
- ItemEBP4367 - Great Northern Signal Technical Drawing, 1918
- ItemEBP4368 - Great Northern Signal Technical Drawing, 1918
- ItemEBP4369 - Great Northern Signal Technical Drawing, 1918