This page of The Last of Us game guide contains information on where to find the comic books in The University chapter. Those items are collectibles-secrets. Our walkthrough indicates the exact location of each artifact and pendant.
Comic #9 - Free Radicals
Right after you start this stage, turn back and follow the path to the very end.
You will find a truck and an SUV wreck there. On the hood of the SUV, there is the ninth comic.