Before revision: Notes References Further reading S. Adams and C. Friedland, "A survey of unmanned aerial vehicle usage for imagery collection in disaster research and management," Jan. 2011.
After revision: The US military has been using drones for surveillance and reconnaissance purposes since the 1960sNotes References Further reading S. Adams and C. Friedland, "A survey of unmanned aerial vehicle usage for imagery collection in disaster research and management," Jan. 2011.