Litrix has interest in dragons, obviously, but other 'beasts' or 'monsters' are also of some interest.
Foes of druidic circles he reads as 'enemies of the Balance' and Wrath of the Ash sounds like it might describe some Red Wyrm
Awakening the Magic in You
Dragonblooded: Dragons and Their Offspring
Warlocks: The Traitors of Magic
Witches of Naugtaure
Wyverns, Wyrms, Drakes and Dragons: The Differences
I will provide more details about The Twenty (at the very least), at some point. I'm not sure how much I will detail the other books. Note that for the PCs to continue to gain the +2 bonuses to Arcana, Nature, and Geography checks for the two geographical regions, the library must be kept together. The Extras can be removed from the library without having any effect on the bonuses, however.
If the PCs make the temple a base of operations, then they can all use the library, borrow a handful of books, and even take specific books with them without issue. Basically, as long as the PCs don't lose them or sell them, it's all good. Lose or sell too many and the bonuses go away.
It might be better if the PCs move the library elsewhere. (Carnell?) The lands around the Temple of Bogphin are quite dangerous and without the temporal stasis to ward the Chamber of the Boots, it will be a risk to leave them in the old ruins. Of course, taking them to Carnell could also be an issue. I know there was a plan to buy the Willowchild Farm and turn it into the group's stronghold in Carnell. Once a fort or fortified manor house is built there, it might be a good place for the library.