Sofia, Girl at Lexicon Library
"It's mostly by donation. It I recall, that guy who died recently, Mr. Pennington I think, was the last one to make any substantial donations, and that was a little over a year ago. There might be the odd donation here or there of one book, though, but even they are only maybe one or two a month on a good month. I like obscure things, let's leave it at that." You get the sense that talking in more detail about what she likes won't just come out without some kind of convincing, if you care to dig deeper.
As for the others, you see books on the most random topics like obscure theories that likely aren't true but have not been disproven yet to historical periods and their more niche events that don't have much weight on the grand scheme of history itself. Despite this, the library has a lot of books, and there even appears to be a second floor, as well as a basement with a sign on it that says "
For approved members only" and has an electronic card lock on it.