Railroad Archives Online
- FondsD0046 - Andrew Klamka Collection
- Cyfres003 - Great Northern Railway Company (U.S.)
- Is-gyfres004 - Library
- 002 - Periodicals
- 50 mwy...
- EitemGNSemaphoreVol5No3 - 'Great Northern Semaphore' March 1928
- EitemGNSemaphoreVol5No4 - 'Great Northern Semaphore' April 1928
- EitemGNSemaphoreVol5No5 - 'Great Northern Semaphore' May 1928
- EitemGNSemaphoreVol5No6 - 'Great Northern Semaphore' June 1928
- EitemGNSemaphoreVol5No7 - 'Great Northern Semaphore' July 1928
- EitemGNSemaphoreVol5No8 - 'Great Northern Semaphore' August 1928
- EitemGNSemaphoreVol5No9 - 'Great Northern Semaphore' September 1928
- EitemGNSemaphoreVol5No10 - 'Great Northern Semaphore' October 1928
- EitemGNSemaphoreVol5No11 - 'Great Northern Semaphore' November 1928
- 1 mwy...