Railroad Archives Online
- FondoD0046 - Andrew Klamka Collection
- Serie003 - Great Northern Railway Company (U.S.)
- Sottoserie004 - Library
- 002 - Periodicals
- 23 in più...
- 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
- 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
- 28 in più...