Railroad Archives Online
- FondoD0046 - Andrew Klamka Collection
- Serie003 - Great Northern Railway Company (U.S.)
- Sottoserie004 - Library
- 002 - Periodicals
- 43 in più...
- Unità documentariaGNSemaphoreVol4No8 - 'Great Northern Semaphore' August 1927
- Unità documentariaGNSemaphoreVol4No9 - 'Great Northern Semaphore' September 1927
- Unità documentariaGNSemaphoreVol4No10 - 'Great Northern Semaphore' October 1927
- Unità documentariaGNSemaphoreVol4No11 - 'Great Northern Semaphore' November 1927
- Unità documentariaGNSemaphoreVol4No12 - 'Great Northern Semaphore' December 1927
- Unità documentariaGNSemaphoreVol5No1 - 'Great Northern Semaphore' January 1928
- Unità documentariaGNSemaphoreVol5No2 - 'Great Northern Semaphore' February 1928
- Unità documentariaGNSemaphoreVol5No3 - 'Great Northern Semaphore' March 1928
- Unità documentariaGNSemaphoreVol5No4 - 'Great Northern Semaphore' April 1928
- 8 in più...