A 1952–1955 study conducted for the United States Air Force (USAF) categorized UFO reports into the following groups: Balloon; Astronomical; Aircraft; Light phenomenon; Birds, Clouds, dust, etc.; Insufficient information; Psychological manifestations; Unknown; and Other.

Authors

• Person: Not available Organization: Wikipedia
  Unidentified flying object - Wikipedia

Sources

• Unidentified flying object - Wikipedia en.wikipedia.org Wikipedia via serper

Referenced by nodes (2)

• United States Department of the Air Force entity
• UFO sightings concept