The Necronomicon
"An image of the law of the dead"

also referred to as the Book of the Dead,
This is a textbook of magic
wrapped in human flesh
and written in blood....
Well, these versions were, anyway. 
If you want to know about the original copy,
you will have to do some digging of your own.
These? Think of them as little Pocket Necronomicons!
They're so cute!

Spell Tomes

Spell Tomes are spell-containing books
you might come across while fighting some
large flying lizards, or doing a seemingly
never-ending list of tasks on a journey... either way,
you'll need them to get your levels up.
OR,
you could just come to our library, stock up on Spell Tomes,
march your way up to whatever beast, creature, or bard
and blast them into Oblivion.
Usually , upon reading a tome, the specific spell contained within is learned, but the tome is destroyed in the process.
These? They'll stay good for you as long as you're good to them!