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An Unconventional Flying Object, Unidentified Flying Object, or simply UFO, is the popular term for any aerial phenomenon that cannot immediately be identified. Some definitions, such as the one used by the United States Air Force (USAF), define a UFO as an object unable to be identified after scrutiny, while other definitions define an object as being a UFO from the time it is first reported as being unidentified, even though most subsequently become IFOs, Identified Flying Objects.

Reports of unidentified aerial phenomena date back to Ancient Alien Hypothesis, but modern reports and the first official investigations began during World War II with sightings of so-called Foo Fighters by Allied airplane crews, and in 1946 with widespread sightings of European "ghost rockets". UFO reports became even more common after the first widely publicized United States UFO sighting, by private pilot #the_kenneth_arnold_sighting in mid-1947. Millions of UFO reports have since been made worldwide.

Use of UFO instead of flying saucer was first suggested in 1952 by Capt. Edward J. Ruppelt, the first director of Project Blue Book, who felt that flying saucer did not reflect the diversity of the sightings. Ruppelt suggested that UFO should be pronounced as a word - you-foe. However, it is generally pronounced by forming each letter: U.F.O. His term was quickly adopted by the Air Force, which also briefly used "UFOB" circa 1954, for Unidentified Flying Object. Ruppelt recounted his experiences with Project Blue Book in his memoir, The Report on Unidentified Flying Objects (1956), also the first book to use the term.

Since its introduction, the term has become heavily associated with flying saucers and Extraterrestrial Hypothesis, though an object may be classified as a UFO independently of opinion as to its origins. Most military and civilian UFO investigations concluded that the majority of objects can be identified either directly, or by applying Occam's Razor.


On April 14, 1561 the skies over Nuremberg, Germany were reportedly filled with a multitude of objects. Woodcut from 1566 by Hans Glaser.
On April 14, 1561 the skies over Nuremberg, Germany were reportedly filled with a multitude of objects. Woodcut from 1566 by Hans Glaser.

Unusual aerial observations have been reported throughout history. Some were undoubtedly astronomical in nature: comet, bright meteor, one or more of the five planets which can be seen with the naked eye, planetary conjunctions, or atmospheric optical phenomena such as sun dogs and lenticular cloud. An example is Halley's Comet, which was recorded first by Chinese astronomers in 240 B.C. and possibly as early as 467 B.C.

"The Baptism of Christ", 1710, by Aert de Gelder. Proponents say this painting depicts UFOs.
"The Baptism of Christ", 1710, by Aert de Gelder. Proponents say this painting depicts UFOs.

Other historical reports seem to defy prosaic explanation, but assessing such accounts is difficult. Whatever their actual cause, such sightings throughout history were often treated as supernatural portents, angels, or other religious omens. Journalist Daniela Giordano says many Medieval-era depictions of unusual aerial objects are difficult to interpret but claims some depicting airborne saucers and domed-saucer shapes are often strikingly similar to UFO reports from later centuries.¹ Art historians, however, explain those objects as religious symbols, often represented in many other paintings of Middle-Age and Renaissance.

Shen Kuo (1031-1095), a Song Chinese government scholar-official and prolific polymath inventor and scholar, wrote a vivid passage in his Dream Pool Essays (1088) about an unidentified flying object. He recorded the testimony of eyewitnesses in 11th century Anhui and Jiangsu (especially in the city of Yangzhou), who stated that a flying object with opening doors would emit a blinding light from its interior (from an object shaped like a pearl) that would cast shadows from trees for ten miles in radius, and was able to take off at tremendous speeds.²

Pre-modern reports

![Photo of an unidentified object New Hampshire in 1870; known as the mystery airship ] (Files/1871UFOpng | right | 323x430 | caption)

Before the terms "flying saucer" and "UFO" were coined in the late 1940s, there were a number of reports of unidentified aerial phenomena in the West. These reports date from the mid-nineteenth to early twentieth century. They include:

Drawing of E. W. Maunder's Nov. 17, 1882, "auroral beam" by astronomer Rand Capron, Guildown Observatory, Surrey, UK, who also observed it.

The Kenneth Arnold sighting

![The report Kenneth Arnold filed in 1947 about his UFO sighting.](Files/Arnold_AAF_drawingjpeg | right | 350x431 | caption)

The post World War II UFO phase in the United States began with a reported sighting by American businessman Kenneth Arnold on June 24, 1947 while flying his private plane near Mount Rainier, Washington. He reported seeing nine brilliantly bright objects flying across the face of Rainier towards nearby Mount Adams at "an incredible speed", which he "calculated" as at least 1200 miles per hour by timing their travel between Rainier and Adams.

Kenneth Arnold holding a picture of a drawing of the crescent-shaped UFO he saw in 1947
Kenneth Arnold holding a picture of a drawing of the crescent-shaped UFO he saw in 1947

His sighting subsequently received significant media and public attention. Arnold would later describe what he saw as being "flat like a pie pan" and as flying "like a saucer would if you skipped it across the water" and also said they were and "half-moon shaped, oval in front and convex in the rear ... they looked like a big flat disk." (One, however, he would describe later as being almost crescent-shaped.) Arnold’s reported descriptions were widely reported upon and gave rise to the terms flying saucer and flying disk.⁵ Arnold’s sighting was followed in the next few weeks by hundreds of other reported sightings, mostly in the U.S., but in other countries as well.

After reports of the Arnold sighting hit the media, other cases began to be reported in increasing numbers. In one instance a United Airlines crew sighting of nine more disc-like objects over Idaho on the evening of July 4. At the time, this sighting was even more widely reported than Arnold’s and lent considerable credence to Arnold’s report.

American UFO researcher Ted Bloecher, in his comprehensive review of newspaper reports, found a sudden surge upwards in sightings on July 4, peaking on July 6-8. Bloecher noted that for the next few days most American newspapers were filled with front-page stories of the new "flying saucers" or "flying discs". Reports began to tail off after July 8, when officials began issuing press statements on the Roswell UFO Incident, in which they explained the debris as being that of a weather balloon.

Over several years in the 1960s, Bloecher (aided by physicist James E. McDonald discovered 853 flying disc sightings that year from 140 newspapers from Canada, Washington D.C, and every U.S. state except Montana.

UFO categorization

Some researchers recommend that observations be classified according to the features of the phenomenon or object that are reported or recorded. Typical categories include:

Hynek system

Dr. J. Allen Hynek developed another system
of description, dividing sightings into six categories.³²

It first separates sightings based on proximity, arbitrarily using 500 feet as the cutoff point. It then subdivides these into divisions based on viewing conditions or special features. The three distant sighting categories are:

The distant classification is useful in terms of evidentiary value, with RV cases usually considered to be the highest because of radar corroboration and NL cases the lowest because of the ease in which lights seen at night are often confused with prosaic phenomena such as meteors, bright stars, or airplanes. RV reports are also fewest in number, while NL are largest.

In addition were three "close encounter" (CE) subcategories, again thought to be higher in evidentiary value, because it includes measurable physical effects and the objects seen up close are less likely to be the result of misperception. As in RV cases, these tend to be relatively rare:

Hynek's CE classification system has since been expanded to include such things as alleged alien abductions (CE4s) and cattle mutilation phenomena.

Vallee system

Jacques Vallee has devised a UFO classification system which is preferred by many UFO investigators over Hynek's system as it is considerably more descriptive than Hynek's, especially in terms of the reported behavior of UFOs.³³

Type I (a, b, c, d): Observation of an unusual object, spherical discoidal, or of another geometry, on or situated close to the ground (tree height, or lower), which may be associated with traces - thermal, luminous, or mechanical effects.

Type II (a, b, c): Observation of an unusual object with vertical cylindrical formation in the sky, associated with a diffuse cloud. This phenomenon has been given various names such as "cloud-cigar" or "cloud-sphere."

Type III (a, b, c, d, e): Observation of an unusual object of spherical, discoidal or elliptical shape, stationary in the sky.

Type IV (a, b, c, d): Observation of an unusual object in continuous flight.

Type V (a, b, c): Observation of an unusual object of indistinct appearance, i.e., appearing to be not fully material or solid in structure.

Source: Jacques and Janine Vallee: Challenge To Science: The UFO Enigma, LC# 66-25843


Ufology is a neologism describing the collective efforts of those who study UFO reports and associated evidence. While not all UFO researchers believe that all UFOs are necessarily extraterrestrial spacecraft, they do believe the area merits research and that the possibility of extraterrestrial spacecraft should be taken seriously.

Battelle Memorial Institute

An Air Force study by Battelle Memorial Institute scientists from 1952-1955 of 3200 USAF cases found 22% were unknowns, and with the best cases, 33% remained unsolved. Similarly about 30% of the UFO cases studied by the 1969 USAF Condon Committee were deemed unsolved when reviewed by the American Institute of Aeronautics and Astronautics (AIAA). The official French government UFO scientific study (GEIPAN) from 1976 to 2004 listed about 13% of 5800 cases as detailed yet inexplicable (with 46% deemed to have definite or probable explanations and 41% having inadequate information).⁶

UFO hypotheses

There are different opinions about the UFO phenomenon. To account for unsolved UFO cases, several hypotheses have been proposed by both proponents and skeptics; a few examples are given below:

Among proponents, some of the more common explanations for UFOs are:

Similarly, skeptics usually propose one of the following explanations:

Other skeptical arguments against UFOs include:

Physical evidence

Besides visual sightings, cases sometimes have indirect physical evidence, including many cases studied by the military and various government agencies of different countries. Indirect physical evidence would be data obtained from afar, such as radar contact and photographs. More direct physical evidence involves physical interactions with the environment at close range - J. Allan Hynek's "close encounter" or Jacques Vallee's "Type-I" cases - which include "landing traces," electromagnetic interference, and physiological/biological effects.

These reported physical evidence cases have been studied by various scientists and engineers, both privately and in official governmental studies (such as Project Blue Book, the Condon Committee, and the French GEIPAN/SEPRA). A comprehensive scientific review of physical evidence cases was carried out by the 1998 Sturrock UFO Panel.

Reverse engineering

Attempts have been made to reverse engineer the possible physics behind UFOs through analysis of both eyewitness reports and the physical evidence. Examples are former NASA and nuclear engineer James McCampbell in his book Ufology, NACA/NASA engineer Paul R. Hill in his book Unconventional Flying Objects, and German rocketry pioneer Hermann Oberth. Among subjects tackled by McCampbell, Hill, and Oberth was the question of how UFOs can fly at supersonic speeds without creating a sonic boom. McCampbell's proposed solution of a microwave plasma parting the air in front of the craft is currently being researched by Dr. Leik Myrabo, Professor of Engineering Physics at the Rensselaer Polytechnic Institute as a possible advance in hypersonic flight.¹² In contrast, Hill and Oberth believed UFOs utilize an as yet unknown anti-gravity field to accomplish the same thing as well as no propulsion and protection of occupants from the effects of high acceleration.

Famous cases


Some studies show that after investigation, the majority of UFOs are usually identified (e.g. identified flying objects). For example, a 1979 study by Allan Hendry, a UFO researcher dedicated to find evidence for extraterrestrial life, found that up to 91.4% of the reports he investigated were either identifiable (91.4%) or could possibly be attributable (7.1%) to known artificial objects and natural phenomena.¹⁴ Hendry's figure for unidentified cases is considerably lower than many official UFO studies such as Project Blue Book or the Condon Report which found unidentified cases made up 6% and 30% of reports respectively.

UFOs have been subject to various investigations over the years, varying widely in scope and scientific rigor. Governments or independent academics in the United States, Canada, the United Kingdom, France, Belgium, Sweden, Brazil, Mexico, Spain, and the Soviet Union are known to have investigated UFO reports at various times.

Among the best-known government studies are Project Blue Book, previously Project Sign and Project Grudge, conducted by the USAF from 1947 until 1969, the secret U.S. Army/Air Force Project Twinkle investigation into [[green fireballs] (1948-1951), and Brazilian Air Force Operation Saucer (1977). Major civilian UFO groups in the US that have conducted extensive investigations were/are NICAP, APRO, [[MUFON], and CUFOS.

American investigations

Starting July 9, 1947, Army Air Force (AAF) intelligence, in cooperation with the FBI, began a formal investigation into selected sightings with characteristics that could not be immediately rationalized, which included Arnold’s and the United crew’s. The AAF used "all of its scientists" to determine whether or not "such a phenomenon could, in fact, occur". The research was "being conducted with the thought that the flying objects might be a celestial phenomenon," or that "they might be a foreign body mechanically devised and controlled."¹⁵ Three weeks later in a preliminary defense estimate, the air force investigation decided that, "This ‘flying saucer’ situation is not all imaginary or seeing too much in some natural phenomenon. Something is really flying around."¹⁶

A further review by the intelligence and technical divisions of the Air Materiel Command at Wright-Patterson Air Force Base reached the same conclusion, that "the phenomenon is something real and not visionary or fictitious," that there were objects in the shape of a disc, metallic in appearance, and as big as man-made aircraft. They were characterized by "extreme rates of climb [and] maneuverability," general lack of noise, absence of trail, occasional formation flying, and "evasive" behavior "when sighted or contacted by friendly aircraft and radar," suggesting a controlled craft. It was thus recommended in late September 1947 that an official Air Force investigation be set up to investigate the phenomenon.

This led to the creation of the Air Force’s Project Sign: One of the earliest government studies to come to a secret ETH conclusion, at the end of 1947, which became Project Grudge at the end of 1948, and then Project Blue Book in 1952. In 1948, they wrote a Estimate of the Situation to that effect. The Air Force Chief of Staff ordered it destroyed. The existence of this suppressed report was revealed by several insiders who had read it, such as astronomer and USAF consultant Dr. J. Allen Hynek and Edward J. Ruppelt, the first head of the USAF's Project Blue Book. ¹⁷

Blue Book closed down in 1970, ending the official Air Force UFO investigations. However, a 1969 USAF document, known as the Bolender Memo, plus later government documents revealed that nonpublic US government UFO investigations continued after 1970. The Bolender memo first stated that "reports of unidentified flying objects which could affect national security... are not part of the Blue Book system," indicating that more serious UFO incidents were already handled outside of the public Blue Book investigation. The memo then added, "reports of UFOs which could affect national security would continue to be handled through the standard Air Force procedures designed for this purpose."

An early US Army study, of which little is known, was called the Interplanetary Phenomenon Unit (IPU). In 1987, British UFO researcher Timothy Good received a letter confirming the existence of the IPU from the Army Director of Counter-intelligence, in which it was stated, "...the aforementioned Army unit was disestablished during the late 1950s and never reactivated. All records pertaining to this unit were surrendered to the U.S. Air Force Office of Special Investigations in conjunction with operation BLUEBOOK." The IPU records have never been released.¹⁸

Air Force Regulation 200-2,¹⁹ issued in 1954, defined an Unidentified Flying Object (UFOB) as "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." The regulation also said UFOBs were to be investigated as a "possible threat to the security of the United States" and "to determine technical aspects involved." As with any then-ongoing investigation, Air Force personnel did not discuss the investigation with the press.

Well known American investigations include:

Canadian investigation

The [[Falcon Lake Incident]] report filed by the Royal Canadian Mounted Police on Stephen Michalak's claimed incident with a UFO.
The Falcon Lake Incident report filed by the Royal Canadian Mounted Police on Stephen Michalak's claimed incident with a UFO.

In Canada, the Department of National Defence has dealt with reports, sightings and investigations of UFOs across Canada. In addition to conducting investigations into crop circles in Duhamel, Alberta, it still identifies the Falcon Lake Incident in Manitoba and the Shag Harbour Incident in Nova Scotia as "unsolved".²⁰

The Canadian studies include Project Magnet (1950-1954) and Project Second Story (1952-1954)

French investigation

In March 2007, the French space agency - Centre National d'Études Spatiales (CNES) - published an archive of UFO sightings and other phenomena online.²¹

French studies include GEIPAN (GEPAN/SEPRA) (1977-), within CNES, the longest ongoing government-sponsored investigation, and the private French COMETA Panel (1996-1999)

British investigation

The UK conducted various investigations into UFO sightings and related stories. The contents of some of these investigations have since been released to the public.

Eight file collections on UFO sightings, dating from 1978 to 1987, were first released on May 14, 2008, to the UK National Archives by the Ministry of Defence (MoD).²² Although kept secret from the public for many years, most of the files have low levels of classification and none is classified Top Secret. 200+ files were made public by 2012. The files are correspondence from the public sent to government officials, such as the MoD and Margaret Thatcher. The MoD released the files under the Freedom of Information Act (UK) due to requests from researchers.²³ These files include, but are not limited to, UFOs over Liverpool and the Waterloo Bridge in London.²⁴

British investigations include The UK's Flying Saucer Working Party. Its final report, published in 1951, remained secret for over 50 years. The Working Party concluded that all UFO sightings could be explained as misidentifications of ordinary objects or phenomena, optical illusions, psychological delusions, or hoaxes. The report stated: ‘We accordingly recommend very strongly that no further investigation of reported mysterious aerial phenomena be undertaken, unless and until some material evidence becomes available’.

A study of UFOs undertaken for the MoD between 1996 and 2000 was publicly released in 2006. The report is titled "Unidentified Aerial Phenomena in the UK Defence Region" and was code-named Project Condign. The report confirmed earlier findings that the main causes of UFO sightings are misidentification of man-made and natural objects. The report noted: "No artefacts of unknown or unexplained origin have been reported or handed to the UK authorities, despite thousands of UAP reports. There are no SIGINT, ELINT or radiation measurements and little useful video or still IMINT." It concluded: "There is no evidence that any UAP, seen in the UKADR [UK Air Defence Region], are incursions by air-objects of any intelligent (extraterrestrial or foreign) origin, or that they represent any hostile intent." In contrast to the official government position, Nick Pope, the head of the UK government UFO desk for a number of years, is an advocate of the Extraterrestrial Hypthesis, based on the inexplicable (to him) cases he reviewed, such as the Rendlesham UFO incident and the so-called Cosford Incident.


The Air Force's Project Blue Book files indicate that approximately 1%²⁵ of all unknown reports came from amateur and professional astronomers or other users of telescopes (such as missile trackers or surveyors). In the 1970s, astrophysicist Peter A. Sturrock conducted two surveys of the AIAA and American Astronomical Society. About 5% of the members polled indicated that they had had UFO sightings. In 1980, a survey of 1800 members of various amateur astronomer associations by Gert Helb and astronomer J. Allen Hynek of the Center for UFO Studies (CUFOS) found that 24% responded "yes" to the question "Have you ever observed an object which resisted your most exhaustive efforts at identification?"

Astronomer Clyde Tombaugh, who admitted to six UFO sightings, including three green fireballs supported the Extraterrestrial Hypothesis for UFOs and stated he thought scientists who dismissed it without study were being "unscientific." Another astronomer was Dr. Lincoln LaPaz, who had headed the Air Force's investigation into the green fireballs and other UFO phenomena in New Mexico. LaPaz reported two personal sightings, one of a green fireball, the other of an anomalous disc-like object. Even later UFO debunker Dr. Donald Menzel filed a UFO report in 1949.

Some studies were neutral in their conclusions, but argued the inexplicable core cases called for continued scientific study. Examples are the Sturrock Panel study of 1998 and the 1970 AIAA review of the Condon Report. Other private or governmental studies, some secret, have concluded in favor of the Extraterrestrial Hypothesis, or have had members who disagreed with the official conclusions. The following are examples of such studies and individuals:

November 1948 USAF Top Secret document citing extraterrestrial opinion
November 1948 USAF Top Secret document citing extraterrestrial opinion

National Press Club press conference on November 12, 2007

On November 12, 2007, Former Arizona Governor Fife Symington moderated a panel of former high-ranking government, aviation and military officials from seven countries at the National Press Club discussing the UFO topic and governmental investigations. The press conference was open for credentialed media and congressional staff only.

Conspiracy theories

UFOs are sometimes an element of elaborate conspiracy theories in which governments are said to be intentionally covering up the existence of aliens, or sometimes collaborating with them. There are many versions of this story; some are exclusive, while others overlap with various other conspiracy theories.

In the US, opinion polls again indicate that a strong majority of people believe the US government is withholding such information. Various notables have also expressed such views. Some examples are astronauts Gordon Cooper and Edgar Mitchell, Senator Barry Goldwater, Vice Admiral Roscoe H. Hillenkoetter (the first CIA director), Lord Hill-Norton (former British Chief of Defense Staff and NATO head), the 1999 high-level French COMETA Report by various French generals and aerospace experts, and Yves Sillard (former director of the French space agency CNES and director of French UFO research organization GEIPAN).

There is also speculation that UFO phenomena are tests of experimental aircraft or advanced weapons. In this case UFOs are viewed as failures to retain secrecy, or deliberate attempts at misinformation: to deride the phenomenon so that it can be pursued unhindered. This explanation may or may not feed back into the previous one, where current advanced military technology is considered to be adapted alien technology (see also: skunk works and Area 51).

It has also been suggested by a few paranormal authors that all or most human technology and culture is based on extraterrestrial contact. See also Ancient Alien Hypothesis.

Allegations of evidence suppression

Some also contend regarding physical evidence that it exists abundantly but is swiftly and sometimes clumsily suppressed by governments, aiming to insulate a population they regard as unprepared for the social, theological, and security implications of such evidence. See the Brookings Report.

There have been allegations of suppression of UFO-related evidence for many decades. There are also conspiracy theories which claim that physical evidence might have been removed and/or destroyed/suppressed by some governments. (See also Men in Black) Some examples are:

UFOs constitute a widespread international cultural phenomenon of the last half-century. Gallup polls rank UFOs near the top of lists for subjects of widespread recognition. In 1973, a survey found that 95 percent of the public reported having heard of UFOs, whereas only 92 percent had heard of US President Gerald Ford in a 1977 poll taken just nine months after he left the White House. (Bullard, 141) A 1996 Gallup poll reported that 71 percent of the US population believed that the government was covering up information regarding UFOs. A 2002 Roper poll for the then Sci-Fi Channel found similar results, but with more people believing UFOs were extraterrestrial craft. In that poll, 56 percent thought UFOs were real craft and 48 percent that aliens had visited the Earth. Again, about 70 percent felt the government was not sharing everything it knew about UFOs or extraterrestrial life.⁴⁴ Another effect of the flying saucer type of UFO sightings has been Earth-made flying saucer craft in space fiction, for example the Earth-made craft Starship C-57D in [Forbidden Planet], and the saucer part of the USS Enterprise in Star Trek.

See also







  1. Giordano, Daniela, "Do UFOs Exist in the History of Arts?" from American Chronicle, 2006-11-13; retrieved 2007-07-27.
  2. Dong, Paul. (2000). China's Major Mysteries: Paranormal Phenomena and the Unexplained in the People's Republic. San Francisco: China Books and Periodicals, Inc. ISBN 0835126765. Pages 69-71.
  3. Before the Wright Brothers...There Were UFOs
  4. Foo-Fighter -- TIME
  5. William Yenne, "Flying Saucers," Secret Weapons of World War II: The Techno-Military Breakthroughs That Changed History (New York: Berkley Books, 2003), 272-274.
  6. Salut, earthlings, The Times, February 5, 2003.
  7. Great balls of Fire a unified theory of ball lightning, UFOs, Tunguska and other anomalous lights, Fireshine Press.
  8. Weather, page 31. 1993.
  9. Journal of Scientific Exploration, Vol. 20, No. 2, pages 215-238, 2006.
  10. Fawcett & Greenwood, pages 81-89; Good, pages 318-322, 497-502.
  11. The Report on Unidentified Flying Objects. Edward J. Ruppelt, 1956. online
  12. Myrabo, Leik N
  13. PARANOIA - People Are Strange: Unusual UFO Cults
  14. Allan Hendry, The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings, 1979, Doubleday & Co., ISBN 0-385-14348-6
  15. Internal FBI memo from E. G. Fitch to D.M. Ladd concerning a request by General Schulgen of USAAF intelligence corps Office of Intelligence Requirements for the FBI to help with their investigation of UFO reports.
  16. Alfred Loedding and the Great Flying Saucer Wave of 1947, Sarah Connors and Michael Hall, White Rose Press, Albuquerque, 1998. Chapter 4: The Onslaught This quotes and summarized the interim report of Lieutenant Colonel George D. Garrett.
  17. The Report on Unidentified Flying Objects. Edward J. Ruppelt. online, Chapt. 3
  18. Timothy Good, Above Top Secret, 1988, William Morrow & Co., ISBN 0-688-09202-0, page 484
  20. Canada's Unidentified Flying Objects: The Search for the Unknown, a virtual museum exhibition at Library and Archives Canada
  21. Site du GEIPAN
  22. UK National Archives
  23. Files released on UFO sightings
  24. AFP Article: Britons 'spotted' UFOs, records say
  25. Catalog of Project Blue Book unknowns
  26. Timothy Good, Above Top Secret, 1988, William Morrow & Co., ISBN 0-688-09202-0, page 23
  27. Document quoted and published in Timothy Good, Need to Know: UFOs, the Military, and Intelligence, 2007, Pegasus Books, ISBN 978-1-933648-38-5, pages 106-107, 115; USAFE Item 14, TT 1524, (Top Secret), 4 November 1948, declassified in 1997, National Archives, Washington D.C.
  28. Good, page 267; Bruce Maccabee, UFO FBI Connection, 2000, Llewellyn Publications, ISBN 1-56718-493-6, pages 75-76
  29. Good, pages 331-335
  30. Richard M. Dolan, UFOs and the National Security State: An Unclassified History, Volume One: 1941-1973, 2000, Keyhole Publishing, ISBN 0-9666885-0-3, page 189; Good, pages 287, 337; The Report on Unidentified Flying Objects. Edward J. Ruppelt. online, Chapt. 16
  31. Good, page 347
  32. The Hynek Classification System, UFO Casebook Files
  33. Vallee Classification System - UFO Evidence
  34. Rhodes_Phoenix
  35. and
  36. and
  37. Strange rocket-like UFO over California/Nevada, June 24, 1950
  38. NCP-12: The White Sands Proof - Maccabee
  39. 1952 newspaper articles of USAF jets being ordered to shoot down saucers
  40. McDonald, 1968 Congressional testimony, Case 41
  41. Good, pages 286-287; Richard M. Dolan, UFOs and the National Security State: An Unclassified History, Volume One: 1941-1973, 2000, Keyhole Publishing, ISBN 0-9666885-0-3, pages 293-295
  42. Detailed article and photos
  43. ; Video testimony for Disclosure Project
  44. CFI - Evidence Page