Sell My College Textbooks

Well I sold my textbooks from this semester (and luckily they took back all of them), but I still have a couple odd ones sitting around that the bookstore wouldn’t take back since they have come out with a new version. I could put them online to sell, but would it be worth it? I’m not sure if anyone would buy them since they are somewhat outdated.

I might just consider this goal done here, but I feel as if I half assed it.

I have a few in good condition that the bookstore did not want to take back. I should put these up online and see if they sell. I don’t remember the address of one of the more popular online places to buy/sell text books. Can someone help me out?