2. Broken Valley, Village, The Black Boar Inn, 3rd floor locked door, strange tomb, 3 parts.
dont know if anyone mentioned it but i found out that the books appear one after the other.
the first book is on the third floor behind a locked door.
then the second will appear on the counter of the bar at the first floor.
then the 3rd will appear next to the woman/smuggler/bandit or whatever she is who sell stuff in the second floor, on top of the pile of books.
after you get the third book, the skill book will appear in the fireplace on the first floor.
by the way, each book give a hint where is the next.