My books for adults fall into two categories — science, and literature. I know — but that's just how it's turned out. There's a little philosophy creeping in, but not enough yet to get its own page. Much of the science could be called history instead. Or as well.
science: Look here for books about science and scientists. The Story of... series is here, including Philosophy, which is not really science but is otherwise homeless, poor thing
books about books: Look here for books about literature, and editions. This page has my earliest publications (on medieval literature) and some more recent study guides