Railroad Archives Online
- FondoD0046 - Andrew Klamka Collection
- Serie003 - Great Northern Railway Company (U.S.)
- Sottoserie004 - Library
- 002 - Periodicals
- 19 in più...
- Unità documentariaGNSemaphoreVol2No8 - 'Great Northern Semaphore' August 1925
- Unità documentariaGNSemaphoreVol2No9 - 'Great Northern Semaphore' September 1925
- Unità documentariaGNSemaphoreVol2No10 - 'Great Northern Semaphore' October 1925
- Unità documentariaGNSemaphoreVol2No11 - 'Great Northern Semaphore' November 1925
- Unità documentariaGNSemaphoreVol2No12 - 'Great Northern Semaphore' December 1925
- Unità documentariaGNSemaphoreVol3No1 - 'Great Northern Semaphore' January 1926
- Unità documentariaGNSemaphoreVol3No2 - 'Great Northern Semaphore' February 1926
- Unità documentariaGNSemaphoreVol3No3 - 'Great Northern Semaphore' March 1926
- Unità documentariaGNSemaphoreVol3No4 - 'Great Northern Semaphore' April 1926
- 32 in più...