4. Oghma Infinium
What it does: When read, the Oghma Infinum grants a permanent boost to all skills linked to the Warrior, the Mage, and the Thief guardian constellations.
Where to find it: Septimus Sigmus Outpost, to the north of Winterhold College
How to get it: Takes a little time this one. Head to Septimus Sigmus Outpost, to visit the insane man who lives there while not on the main questline and he will request two lots of things from you: an imprint of an Elder Scroll from some Dwemer ruins, blood from an Orc, a Falmer, a Dark Elf, a Wood Elf and a High Elf, which can be looted from their dead bodies. Hand over the requested goodies and he will eventually hand over the Oghma Infinium.