- eBookThe Homing PigeonUnited States. War Department
- eBookVisual SignalingUnited States. Army. Signal Corps
- eBookVisual SignalingUnited States. Army. Signal Corps
- eBookThe Homing PigeonUnited States. War Department
- eBookVisual SignalingUnited States. Army. Signal Corps
- eBookVisual SignalingUnited States. Army. Signal Corps