There are no books specifically about the librarian but he still appears in quite a few and is one of the disc's most popular characters. His first appearence was at the start of "The Light Fantastic" where the infamous accident took place changing him from a human into an orangutan. He liked it so much he wouldn't let anyone change him back.
Trying to describe the librarian is no easy task. It's not that I don't have an understanding of his personality it's just that putting it into words is fairly tricky. The fact that all he ever says is "ook" and every now and then "eek" doesn't exactly help matters. He's helpfull.....a bit violent......doesn't like being called monkey....is partial to a bannana or two.
The rest of the Unseen University crew don't have books specifically about them either but also appear in quite a few. Although Windle Poons does have a starring role in "Reaper Man". The bunch of lethargic old wizards who teach at the disc's premier university make their first important appearence in "Sourcery".