Specific job skill book

So i've wondered about something, which way, beside Neo city quest chain and silant crosader, i can get Specific job skill book which are not part of the unleased event?

and btw, are the skill book from Unleased event are only for lvl 30 skill?

The LHC quest line gives a class Mystery Mastery Book that always gives a 20 book.

And all the class specific Mystery Mastery Books should give both level 20 and level 30 books, except for Xenon and Jett, which are still not fixed.