幽浮學
參考資料

↑  Tuomela, Raimo. . Springer. 1985: 234. ISBN 90-277-2098-3.
↑  Feist, Gregory J. . Yale University Press. 2006: 219. ISBN 0-300-11074-X.
↑  Restivo, Sal P. . Oxford University Press US. 2005: 176. ISBN 0-19-514193-8.
↑  Shermer, Michael (编).  (PDF). ABC–CLIO, Inc. 2002  [16 December 2013]. ISBN 978-1-57607-653-8. （原始内容存档 (PDF)于2016-08-11）.
↑  . 美国科学前沿（英语：）. 公共广播电视公司. Chedd-Angier Production Company. 1997–1998. （原始内容存档于2006）.
↑  . （原始内容存档于9 October 2009）.
↑  Fraknoi, Andrew. . Astronomical Pseudo-Science: A Skeptic's Resource List. Astronomical Society of the Pacific. October 2009  [2 November 2011]. （原始内容存档于2016-03-04）.
↑   (PDF). Iowa Academy of Science. July 1986. （原始内容 (PDF)存档于26 June 2007）.
↑   (PDF). NSA.   [2021-10-04]. （原始内容存档 (PDF)于2021-10-04）. Sir Bernard Lovell, one of the world's leading radio astronomers, has calculated that, even allowing for a margin of error of 5000%, there must be in our own galaxy about 100 million stars which have planets of the right chemistry, dimensions, and temperature to support organic evolution.
↑   (PDF). NSA.   [2021-08-18]. （原始内容存档 (PDF)于2021-07-09）.
1 2  Peter Gersten, Frontiers of Science.  (PDF). NSA.   [2021-08-18]. （原始内容存档 (PDF)于2021-07-09）. New evidence for the existence of unconventional aerial objects relies no longer on the credibility of civilian reports but on the records of scientists, military personnel, intelligence analysts, law enforcement officers and other reliable and responsible people. Their testimony can be found in three thousand pages of previously classified documents on UFOs released (mostly through Freedom of Information Act suits) over the past few years by the Departments of State / Army / Navy /Air Force/Defense, the Federal Bureau of Investigation, the National Securitv Agency, the Detense Intelligence Agency and the central Intelligence Agency.
↑  . NSA.   [2021-08-18]. （原始内容存档于2021-08-23）.
↑  . NSA.   [2021-08-18]. （原始内容存档于2021-08-13）.
↑  not included in Hynek's original classification scheme.
↑  THE UFO EXPERIENCE: A scientific enquiry (1972), ISBN 978-1-56924-782-2
↑  . 大公网. 2018-05-27  [2020-07-22]. （原始内容存档于2020-07-22）.
↑  Denzler (2003), p. 15
↑  Edward U.Condon. . 1968  [May 4, 2010]. （原始内容存档于2017-09-12）. Our general conclusion is that nothing has come from the study of UFOs in the past 21 years that has added to scientific knowledge. Careful consideration of the record as it is available to us leads us to conclude that further extensive study of UFOs probably cannot be justified in the expectation that science will be advanced thereby.
↑  Wired. . 2006-05-10  [May 4, 2010]. （原始内容存档于2013-06-15）.
↑  Ministry of Defense.  (PDF): 4. December 2000  [May 5, 2010]. （原始内容存档 (PDF)于2012-10-26）. That UAP exist is indisputable …[they] clearly can exhibit aerodynamic characteristics well beyond those of any known aircraft or missile – either manned or unmanned.
↑  Ministry of Defense.  (PDF): 10. December 2000  [May 5, 2010]. （原始内容存档 (PDF)于2012-10-26）.
↑  Ministry of Defense.  (PDF): 11. December 2000  [May 5, 2010]. （原始内容存档 (PDF)于2012-10-26）.
↑   (PDF). NSA.   [2021-08-18]. （原始内容存档 (PDF)于2021-07-09）. Sir Bernard Lovell, one of the world's leading radio astronomers, has calculated that, even allowing for a margin of error of 5000%, there must be in our own galaxy about 100 million stars which have planets of the right chemistry, dimensions, and temperature to support organic evolution.
↑   (PDF). NSA.   [2021-08-18]. （原始内容存档 (PDF)于2021-07-09）.
↑  . NSA.   [2021-08-18]. （原始内容存档于2021-08-23）.
↑  . NSA.   [2021-08-18]. （原始内容存档于2021-08-13）.