Not trying to be rude, man, but most of these have nothing to do with academic study of the Devil. This list is for scholarly works, not pop culture collections or religious fluff:

Krampus: The Devil of Christmas: Pre-WWI Krampus Postcard Reproductiions is literally a postcard reprint book. It's a novelty item, not academic in any way.

The Krampus and the Old, Dark Christmas: Roots and Rebirth of the Folkloric Devil is entertaining folklore, sure, but it's still a seasonal deep dive and not even close to demonology scholarship.

Comics Go To Hell is just a rundown of comic book appearances of the Devil. That’s pop culture history, not theological or historical research.

Hell: A Guide (Answers to All Your Questions about the Devil is written by a Catholic author to explain the Devil from a modern religious perspective. It’s devotional, not critical or academic.

Who in Hell...: A Guide to the Whole Damned Bunch is a tongue-in-cheek reference guide. It doesn’t belong on any list claiming to be about scholarly work.

The Penguin Book of Hell and Diableries: Stereoscopic Adventures in Hell actually have some substance, but the rest don’t belong on this list at all.