The following affiliate links will take you to the PDFs for retro clones of AD&D and each of the AD&D manuals. All links are Affiliate Links.
See OSRIC for a free AD&D compatible set of rules.
You can read my OSRIC unboxing post here.
Labyrinth Lord Advanced Edition Companion
Astonishing Swordsmen & Sorcerers of Hyperborea
See the list on Taxidermic Owlbear in the section on Advanced Dungeons & Dragons 1st Edition
You can order PDFs and Print On Demand copies with the Re-Print covers from DriveThruRPG or DMSGUILD. Note: They are linked so what you purchase on DMSGUILD is available on your DriveThruRPG Library.
Players Handbook Also available POD.
Monster Manual Also available POD.
Dungeon Masters Guide Also available POD.
World of Greyhawk Fantasy Game Setting
