So what I would suggest is, that books should be far less in numbers, but much more specialized (for example in terms of "Topic" and "Quality"). You would have to gather these books and store them in a library inside the research bench in order to research a appropriate technology. Of course these books wouldn't be consumed during the research process.
Example:
Topics: Physics, Chemistry, Biology, ...
Grades: Basic, Advanced and Special (like a book about metallurgy as a very special and rare one in the Physics-section)
Practical example: Weapon smiting
* for level 1 and 2 you need a Basic physics book in your library.
* for level 3 you need a Basic physics book and a Advanced physics book in your library.
* for level 4 you need two Advanced physics books (Now the Basic physics book doesn't matter anymore for the Weapon smiting tech-tree, but the very same book can still be of use for the first levels of other physics-related technologies.)
* for level 5 you need one Advanced physics book and one Basic chemistry book.
* and a really high level of weapon smiting would require a Special book about Metallurgy.
I think, the challenge to complete your library could be a nice addition to players experience. These books could lay in abandoned ruins ore be locked away inside the temples of Orkan (because Knowledge is the natural enemy of Faith
). So you would have an actual reason to visit these places and search for hidden treasures.