I was quite a poor college student, and thus had to sell most of my course books back to the university at the end of each quarter/semester in order to afford my books for the next quarter/semester. I wish I could've kept most of them, and I dreaded each time I had to let them go.
I was a graphic design major, and there was a rare few books that I just refused to let go of because of how much inspiration was packed in them. They were worth having nothing but Top Ramen and eggs to live on for a few extra weeks haha... My precious thick-as-fuck fine art history books. I graduated college in 1999, so it wouldn't surprise me if some of the content I was exposed to is not used or emphasized upon as much anymore.
I even kept my Modern Art class book, just to keep as a reminder of the awful degradation that occurred. :(