There’s a review of the original Wilderlands D&D campaign setting, produced by the Judges Guild back in the ’70s, over here. As a big Judges Guild fan, I had this setting and the others that went with it. I used to lay out all the maps that came with them in my bedroom and see how they connected to each other. It was awesome!
D&D was heavily influenced by the fantasy books that were popular in the late ’60s and early ’70s. In his famous “Appendix N” – found at the back of the AD&D Dungeon Master’s Guide – Gary Gygax listed a series of books and authors which he described as “Inspirational and Educational Reading.” Unsurprisingly, those in the “Old School” or OD&D community return frequently to this appendix and discuss it, and possible additions to it, on their blogs and forums.