Latest developments and cost. (4000 w.) (70834)
Service record of position-light signals
R S E
1916
Ills.
Aufsatz (Zeitschrift)
Englisch
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Position-light signals for railroad service
Engineering Index Backfile | 1917
|"Position light" signals on the Pennsylvania
Engineering Index Backfile | 1916
Position-light signals on Pennsylvania railroad
Engineering Index Backfile | 1918
The development of position-light signals
Engineering Index Backfile | 1921
|Replacing semaphores with position-light signals on Norfolk and Western
Engineering Index Backfile | 1936