Railroad Archives Online
- FondoD0046 - Andrew Klamka Collection
- Serie003 - Great Northern Railway Company (U.S.)
- Sottoserie004 - Library
- 002 - Periodicals
- 46 in più...
- 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
- Unità documentariaGNSemaphoreVol5No5 - 'Great Northern Semaphore' May 1928
- Unità documentariaGNSemaphoreVol5No6 - 'Great Northern Semaphore' June 1928
- Unità documentariaGNSemaphoreVol5No7 - 'Great Northern Semaphore' July 1928
- 5 in più...