I find, buy & read a lot of old UFO books, usually just cheap mass market out of print paperbacks. It's weird sometimes, because I literally grew up obsessively reading these things, so every now and then I get a weird deja vu feeling coming across a paragraph or photograph that I know I probably read in 1976. I grew up in a very book-deprived town; there were only a couple regular bookstores, Town Crier (which doubled as a smoke shop) and B. Dalton, but even that didn't come til the 80's, I believe. I actually miss B. Dalton's, dammit. I can smell them both.
There was a creepy used bookstore, on the 'wrong' side of the tracks, called Dean's Books that my sister used to beg my mom to take us to; I hated it because there was cordoned-off a porn section that...well, I'll leave that beautiful detail out of the story. I wonder if it's still there--it was as of 1996, when we took a ton of my dad's books there to sell after he died. We thought we would get so much money, but he offered us like $3. We were insulted, so ended up dropping them off at the thriftstore. Now, being a used book seller, I actually think that guy was being generous.
At Dean's books, so long ago, my sister was busy looking for novels that should have/would have probably been over her head, and I used to scrounge for any kind of UFO or paranormal type books I could find. I remember my mom saying "don't you have that one already..." because they all pretty much had the same cover, with "UFOs, blah blah" emblazoned across the cover.
While I'm out bookscouting now, of course I keep my eyes open for UFo books. I thought I'd start writing some brief reviews. Even though most of these books are out of print, many can be found at amazon, used, for literally a penny + shipping. Obviously, some things are outdated, but there are a lot of old, rather forgotten cases mentioned, and all kinds of ideas that have since become unfashionable. I'm all about UFO theories, so for me it's a great way to get information that might not be in the mainstream now.
Soon, I will post a review of one I just finished--Alien Agenda (not the Marrs book) by Clifford Wilson. He's got the demons going. Yee-haw, dammit.