Reddit reviews Operation Trojan Horse: The Classic Breakthrough Study of UFOs

Mystery airships was a series of UFO sightings in the US between 1896 and 1897, making it the first massive UFO appearance in recorded history. A similar series of events took place (also in the US) between 1909 and 1912.

The UFOs sighted in 1896-97 closely resembled airships (hence the name) but vastly outperformed all airships built to date, including the Zeppelin LZ1 which was launched in 1900, starting the "Golden Age" of airships. Several individuals claimed to have build these highly advanced airships but no evidence was published after 1897.

In 1909-12, a similar wave ("flap") of UFOs was seen in the US, only this time it were fixed-wing aircraft instead of airships. Appearing in massive numbers in those years, they very similarly disappeared without a trace after 1912.

The official sources have dismissed both events as mass hysteria fueled by hoaxes and falsely interpreted natural phenomena.

John Keel in his UFOs: Operation Trojan Horse (1970) argues that the mystery airships were, in fact, not of extraterrestrial origin but rather, of the "ultraterrestrial", i.e. built by an very advanced civilization living on Earth alongside humanity (though they might be humans, too, only far ahead of the mainstream science). He also ties the UFO sightings to many unexplained supernatural phenomena.

http://www.amazon.ca/Operation-Trojan-Horse-Classic-Breakthrough/dp/1938398033

> "The real UFO story must encompass all of the many manifestations being observed. It is a story of ghosts and phantoms and strange mental aberrations; of an invisible world that surrounds us and occasionally engulfs us; of prophets and prophecies, and gods and demons. It is a world of illusion and hallucination where the unreal seems very real, and where reality itself is distorted by strange forces which can seemingly manipulate space, time, and physical matter-forces that are almost entirely beyond our powers of comprehension."

> John A. Keel (March 25, 1930 - July 3, 2009) was an American journalist and influential UFOlogist best known as the author of "The Mothman Prophecies." In the 1950s, he spent time in Egypt, India, and the Himalayas investigating snake charming cults, the Indian rope trick, and the legendary Yeti, an adventure that culminated in the publication of his first book, "Jadoo." In the mid-1960s, he took up investigating UFOs and assorted forteana and published his first knockout UFO book, "UFOs: Operation Trojan Horse," in 1970. The book shredded the then trendy nuts-and-bolts extraterrestrial hypothesis for UFOs in favor of one that linked UFOs to a variety of paranormal and supernatural phenomena that have taken place throughout history. Keel was one of the first to note that the UFO phenomenon appears in different disguises-and that one could not begin to decipher this great mystery without first taking into account its many and varied deliberate deceptions. Other than a few corrections, this Anomalist Books edition essentially follows the original 1970 edition of "UFOs: Operation Trojan Horse."

Three at random:

Operation Trojan Horse: The Classic Breakthrough Study of UFOs by John Keel - also consider The Mothman Chronicles but it's not specifically about the source/cause of UFOs, he just makes commentary about that subject at spots in the book.

The UFO Singularity by Micah Hanks - haven't read it yet (it's in the post at the moment) but in his Mysterious Universe interview of a week or two ago he made it clear he had varied views on the cause/source of UFOs.

UFOs, Area 51, and Government Informants: A Report on Government Involvement in UFO Crash Retrievals by Grant Cameron and Scott Craig - written assuming the 'alien presence' hypothesis, obviously.

Graham Hancock has some interesting/disturbing theories regarding the alien phenomena, but I don't think any of his books specifically deal with it, I've just heard him discuss them in interviews.