- E-bookThe Homing PigeonUnited States. War Department
- E-bookVisual SignalingUnited States. Army. Signal Corps
- E-bookVisual SignalingUnited States. Army. Signal Corps
- E-bookThe Homing PigeonUnited States. War Department
- E-bookVisual SignalingUnited States. Army. Signal Corps
- E-bookVisual SignalingUnited States. Army. Signal Corps