The first of these is J. Allen Hynek's seminal The UFO Experience: A Scientific Inquiry, the book which coined the "Close Encounter" classification scheme. Originally published in 1972, this book covered Hynek's years as a "scientific advisor" to the Air Force's "Project Blue Book", which was the official "clearinghouse" for info on UFO's. Hynek was not a "UFO buff" when he got involved in this, he was the chief astronomer running Ohio State's observatory at the time that the Air Technical Intelligence Center was being run out of Wright-Patterson AFB in Dayton ... they needed an astronomer to say "the observer was seeing Venus", and he was the nearest "A-list" specialist, and for 22 years (1947-1969, through "Project Sign", "Project Grudge" and "Project Blue Book") he was their "scientific advisor".
Hynek, was, however, a scientist (he ended up in a tenured "chair" position at Northwestern, after all), and he was aghast at what he saw happening in the Air Force's approach to the whole UFO issue. The UFO Experience (which is, by the way, still in print in a paperback edition) was his "uncovering" of how badly managed the "official government response" to UFO phenomena had been, as well as his suggestions as to how to classify/approach future incidents.
Being from 1972, the book has certain "quaint" aspects ... it is easy to forget today how recently computer access has spread to the general population. One of his repeated pleas was to get the reports into "machine readable" format, which in those days (which I recall from my own highschool years) involved punching cards, which then were processed to punch a paper tape, which then was fed into a machine which sent that data over a phone line to "a computer" which would likely store the information on magnetic tape reels. This does beg the question, however, of why there haven't been HUGE strides in UFO research over, say, the past 20 years when computers have become more and more ubiquitous ... using Hynek's "Strangeness" and "Probability" ratings and his "prototype" classifications (nocturnal lights, daylight disks, radar-visual, and Close Encounters of the 1st, 2nd, and 3rd kinds), one would think that scientifically-minded "UFO buffs" would have by now amassed quite a dramatic amount of data. As Hynek points out, even the Blue Book (which existed largely to explain away all reports) had something like 25% "unidentified" sightings, but I can't say that I've seen much convincing material along these lines of recent vintage.
Also, Hynek was writing in a pre-"X-Files" world. From his perspective, most of what was wrong with the "official government approach" was due to institutional factors which arose more out of ignorance of "scientific approaches" and bias against the topic of UFOs in general, than any conspiracy to "cover up the truth". He details how frequently incidents with a LOT of data, many eye-witnesses, etc. were simply ignored, or only barely investigated ... the interest in the Air Force being to find the quickest route to "explain away" the event. However, there was ONE case which made me think of today's "paranoia" mode, in which he notes that a "government investigator" (in plain clothes, but who was recognized as an Air Force officer) had gone on-scene to interview witnesses before the incident had been officially reported ... from Hynek's perspective in 1972 it's "odd", from today's standpoint it does make one wonder if there was a whole separate secret group in the Air Force which was actually studying these events, and allowing Blue Book to run it's bumbling whitewash program as "cover".
Anyway, it was an interesting read, and if you have an interest in UFOs, you should have this book. As I noted, this is a fancy-schmancy edition, and it is, amazingly, available for as little as $2.75 for a "new" copy via Amazon's new/used vendors (although you could get a "good/acceptable" copy of the paperback for as little as 1¢, compared to the current paperback edition's cover price of $12.95), which seems like a pretty good deal!