A link to the page or something like "32x32 Dungeon Pack by Alex's Assets" works or you can just do "Alex's Assets". If you want to do it some other way then that's fine as well, it's really up to you.
Sorry, I don't. When I did the artwork, I didn't come up with any names, I just made it, so there were never any names to begin with. Feel free to call them anything you like.