From what I can remember, its only spells you can buy from shops. The skills for the other classes don't come in the form of books.
But you can find items with skills for the other classes. In fact, heres a little hint for that. <span class='standouttext'>Spoiler : </span><span class='spoiler'> Instead of putting points into the lockpick skill, you get about 2 or 3 later on in quests alone, and you usually find a few items by the end of the game that put into such skills. I personnally added twice into it in my warrior, and it helped in the beginning, but it was unneeded later. </span> <img src="/ubbthreads/images/graemlins/freak.gif" alt="" /> So you'd have to choose to put into it or not.
Killerzzz