Charles Schulz's Peanuts, for whatever reason, has one of the more dedicated fan communities on the internet. The Peanuts Fandom wiki is an invaluable resource for anything you might want to know about the strip, from obscure characters to running jokes to the gang’s unofficial cameo appearances in later media like Family Guy. While Peanuts itself has been the subject of broad academic discussion since the end of its original run, its wiki has that dense block of exhaustive well-organized trivia that you only really get from dedicated fans. (They probably ought to get the Peanuts wiki off of Fandom at some point.)