honestly i cant remember, i just started going to every possible nook and cranny in the areas i could go to and looking, i grinded up levels so i could beat the scion bosses hidden across the map to make sure i got all the books because i couldnt remember how many books there were total.
there are four books to find, when you have all four books you speak to mandrake (carrot in the box in the alley) in sylva city, because there isnt a side quest log yet im sharing this.