In The Keep on the Borderlands (1980) in the Caves of Chaos the doors to rooms 3 and 11 are locked. Does the adventure disclose the location of each door's key? Are there other hard to find keys elsewhere in the adventure that I've overlooked that I should be aware of?
Note: My current campaign involves several adventures from the Dungeon #116 article "The 30 Greatest D&D Adventures of All Time" (68-81) and The Keep on the Borderlands is the campaign's start. I'm prepping for the PCs' assault on the caves and only part way through (hence the second question, above), but this detail was bothering me. Further, despite my age, I neither ran Keep nor played it back in the day, so pity my inexperience and unfamiliarity and forgive me if this is an old and obvious question to all my fellow grognards. I tried researching this question myself, but the Google kept returning results for Borderlands 2 golden keys (which is okay—I like the Borderlands series (though Pre-sequel is better)—but definitely not what I wanted!).
I've tagged this question dungeons-and-dragons although the adventure's for basic D&D and my campaign uses the D&D 3.5e rules because the adventure's been published for, I think, every D&D edition, and I suspect answers might need to range beyond the version I'm using.