Thomas E. Bullard, "UFOs: Lost in the Myths", pages 141 - 191 in "UFOs, the Military, and the Early Cold War Era", pages 82 - 121 in "UFOs and Abductions: Challenging the Borders of Knowledge" David M. Jacobs, editor; 2000, University Press of Kansas, ISBN 0-7006-1032-4
Jerome Clark, The UFO Book: Encyclopedia of the Extraterrestrial, 1998, Visible Ink Press, ISBN 1-57859-029-9. Many classic cases and UFO history provided in great detail; highly documented.
Curran, Douglas. In Advance of the Landing: Folk Concepts of Outer Space. (revised edition), Abbeville Press, 2001. ISBN 0-7892-0708-7. Non-sensational but fair treatment of contemporary UFO legend and lore in N. America, including the so-called "contactee cults." The author traveled the United States with his camera and tape recorder and directly interviewed many individuals.
Hall, Richard H., editor. The UFO Evidence: Volume 1. 1964, NICAP, reissued 1997, Barnes & Noble Books, ISBN 0-7607-0627-1. Well-organized, exhaustive summary and analysis of 746 unexplained NICAP cases out of 5000 total cases — a classic.
Hall, Richard H. The UFO Evidence: A Thirty-Year Report. Scarecrow Press, 2001. ISBN 0-8108-3881-8. Another exhaustive case study, more recent UFO reports.
Hendry, Alan. The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings. New York: Doubleday & Co., 1979. ISBN 0-385-14348-6. Skeptical but balanced analysis of 1300 CUFOS UFO cases.
Hynek, J. Allen. The UFO Experience: A scientific inquiry. Henry Regnery Co., 1972.
Hynek, J. Allen. The Hynek UFO Report. New York: Barnes & Noble Books, 1997. ISBN 0-7607-0429-5. Analysis of 640 high-quality cases through 1969 by UFO legend Hynek.
Rose, Bill and Buttler, Tony. Flying Saucer Aircraft (Secret Projects). Leicester, UK: Midland Publishing, 2006. ISBN 1-85780-233-0.
Sagan, Carl & Page. Thornton, editors. UFOs: A Scientific Debate. \Cornell University Press, 1996. ISBN 0-7607-0192-2. Pro and con articles by scientists, mostly to the skeptical side.
Philip Plait (2002). Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing "Hoax". John Wiley & Sons, ISBN 0-471-40976-6. (Chapter 20: Misidentified Flying Objects: UFOs and Illusions of the Mind and Eye.)
Carl G. Jung, "Flying Saucers: A Modern Myth of Things Seen in the Skies" (translated by R.F.C. Hull); 1979, Princeton University Press, ISBN 0-691-01822-7
เชิงประวัติศาสตร์
Richard M. Dolan, UFOs and the National Security State: An Unclassified History, Volume One: 1941 - 1973, 2000, Keyhole Publishing, ISBN 0-9666885-0-3. Dolan is a professional historian.
Downes, Jonathan Rising of the Moon. 2nd ed. Bangor: Xiphos, 2005.
Lawrence Fawcett & Barry J. Greenwood, The UFO Cover-Up (Originally Clear Intent), 1992, Fireside Books (Simon & Schuster), ISBN 0-671-76555-8. Many UFO documents.
Timothy Good, Need to Know: UFOs, the Military, and Intelligence, 2007, Pegasus Books, ISBN 978-1-933648-38-5. Update of Above Top Secret with new cases and documents
Edward J. Ruppelt, The Report On Unidentified Flying Objects, 1956, Doubleday & Co. online. A UFO classic by insider Ruppelt, the first head of the USAF Project Blue Book
LeRoy F. Pea, Government Involvement in the UFO Coverup, or earlier title History of UFO Crash/Retrievals", 1988, PEA RESEARCH.[3]
เชิงเทคโนโลยี
Paul R. Hill, Unconventional Flying Objects: a scientific analysis, 1995, Hampton Roads Publishing Co., ISBN 1-57174-027-9. Analysis of UFO technology by pioneering NACA/NASA aerospace engineer.
James M. McCampbell, Ufology: A Major Breakthrough in the Scientific Understanding of Unidentified Flying Objects, 1973, 1976, Celestial Arts, ISBN 0-89087-144-2full-text online. Another analysis by former NASA and nuclear engineer.
James M. McCampbell, Physical effects of UFOs upon people, 1986, paperเก็บถาวร 2009-03-26 ที่ เวย์แบ็กแมชชีน.
Antonio F. Rullán, Odors from UFOs: Deducing Odorant Chemistry and Causation from Available Data, 2000, preliminary paperเก็บถาวร 2009-03-26 ที่ เวย์แบ็กแมชชีน.
Jack Sarfatti, "Super Cosmos", 2005 (Authorhouse)
S. Krasnikov (2003). "The quantum inequalities do not forbid spacetime shortcuts". Physical Review D. 67: 104013. doi:10.1103/PhysRevD.67.104013. See also the "eprint version". arXiv.
L. H. Ford and T. A. Roman (1996). "Quantum field theory constrains traversable wormhole geometries". Physical Review D. 53: 5496. doi:10.1103/PhysRevD.53.5496. See also the "eprint". arXiv.