Railroad Archives Online
- FondsD0046 - Andrew Klamka Collection
- Série003 - Great Northern Railway Company (U.S.)
- Sous-série004 - Library
- 002 - Periodicals
- 52 en plus...
- PièceGNSemaphoreVol5No5 - 'Great Northern Semaphore' May 1928
- PièceGNSemaphoreVol5No6 - 'Great Northern Semaphore' June 1928
- PièceGNSemaphoreVol5No7 - 'Great Northern Semaphore' July 1928
- PièceGNSemaphoreVol5No8 - 'Great Northern Semaphore' August 1928
- PièceGNSemaphoreVol5No9 - 'Great Northern Semaphore' September 1928
- PièceGNSemaphoreVol5No10 - 'Great Northern Semaphore' October 1928
- PièceGNSemaphoreVol5No11 - 'Great Northern Semaphore' November 1928
- PièceGNSemaphoreVol5No12 - 'Great Northern Semaphore' December 1928