Railroad Archives Online
- FondoD0046 - Andrew Klamka Collection
- Serie003 - Great Northern Railway Company (U.S.)
- Sottoserie004 - Library
- 002 - Periodicals
- 28 in più...
- Unità documentariaGNSemaphoreVol3No5 - 'Great Northern Semaphore' May 1926
- Unità documentariaGNSemaphoreVol3No6 - 'Great Northern Semaphore' June 1926
- Unità documentariaGNSemaphoreVol3No7 - 'Great Northern Semaphore' July 1926
- Unità documentariaGNSemaphoreVol3No8 - 'Great Northern Semaphore' August 1926
- Unità documentariaGNSemaphoreVol3No9 - 'Great Northern Semaphore' September 1926
- Unità documentariaGNSemaphoreVol3No10 - 'Great Northern Semaphore' October 1926
- Unità documentariaGNSemaphoreVol3No11 - 'Great Northern Semaphore' November 1926
- Unità documentariaGNSemaphoreVol3No12 - 'Great Northern Semaphore' December 1926
- Unità documentariaGNSemaphoreVol4No1 - 'Great Northern Semaphore' January 1927
- 23 in più...