- Libro electrónicoThe Homing PigeonUnited States. War Department
- Libro electrónicoVisual SignalingUnited States. Army. Signal Corps
- Libro electrónicoVisual SignalingUnited States. Army. Signal Corps
- Libro electrónicoThe Homing PigeonUnited States. War Department
- Libro electrónicoVisual SignalingUnited States. Army. Signal Corps
- Libro electrónicoVisual SignalingUnited States. Army. Signal Corps