The Colleges of Magic (WAR History and Lore)  

If you are travelling west on the path at 11k/21k and look to your south you will see a small rise at the top of which is a tree (on your left) and a boulder (on your right). Run up the rise and in a hole in between the rock and the tree is A Dusty Tome (11k, 24k). Interacting with the book will grant you the unlock.

History & Lore in Nordland