The Ranger's Reading Primer artifact can be found at Southern Udûn Pass, in the eastern part of Udûn.
Ranger's Reading Primer, Third Age, circa 2915
The Rangers of Gondor are not just powerful warriors, they also perform a host of duties throughout the Kingdom. Depending on the circumstances, a Ranger may be called upon to serve as a mediator, a judge, a medic and, on occasion, even a teacher.
Rangers have been known to carry basic Reading Primers and, during their stays in villages where opportunities for learning are scant, to select a few favored pupils and show them how to read and write.
The memory point attached to the primer is of its original owner, Hirgon, teaching his Outcast lover, Eryn, to read:
Sound it out now…
FEE-AH-NOR… Fëanor. Why must you put me through this, Hirgon?
There's no one to blame but yourself. You begged me to teach you the words in my books.
I regret that now. What use is the page here in Mordor?
Here. Look at this. A note for you.
My love. Be… my… knife…
Wife? Yes, Hirgon. I am yours.