Who are Darmok and Jalad and what is Kalenda's? (asking for an explanation of XKCD 902) was closed as general reference.
I don't understand what the general reference is supposed to be. The top Google hit, which is mentioned in the comments, is Explain XKCD. The explanation there is incomplete: it explains the reference to the Star Trek episode Darmok, which explains Darmok and Jalad but not Kalenda; and it ends with a request for more information. Other references cited in comments or answers are the Wikipedia and Memory Alpha articles for that episode, which do explain why the episode is relevant but (especially in the case of Memory Alpha) buried inside a wall of text.
So at most we have one clear but unreviewed and incomplete explanation (Explain XKCD), and one peer-reviewed but unclear explanation (Wikipedia). And no one's given a full answer (who or what is Kalenda). How is this question general reference?