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| Aerial reconnaissance (3) |
| Military reconnaissance (3) |
| World War, 1914-1918--Aerial operations (3) |
| World War, 1914-1918--Reconnaissance operations (3) |
| Air warfare (2) |
| Airships (1) |
| Balloons (1) |
| Bombing, Aerial (1) |
| Fighter plane combat (1) |
| Military airships (1) |