I agree with Tech Knowledge to research spellbooks and Arcane Knowledge to learn spells, and levels from a particular spellbook.

I really like the idea of researching specific levels of different spells (such as air, earth, fire, water) like in this post (and others I can't seem to find at the moment).  So Arcane Knowledge would be used to first research specific first level spells of elements you know (ie. have researched via Tech Knowledge), then you would increase the level of each spellbook you've researched or gained access to, rather than being able to learn *a new level of all spellbooks* at once.  Others have supported this idea as well, and along with making spells from different spellbooks more unique, it would allow every game to be different, because you'd have to specialize in certain spellbooks rather than simply learning the whole lot at once.

EDIT: Made name shorter.

Best regards,
Steven.