After the first meeting with Madeleine, Charles Theverner addresses his pet raven named Villon, after the French poet François Villon, and quotes from Villon's "Ballade des dames du temps jadis" ("Ballad of the Ladies of Times Past"): "Où sont les neiges d'antant?" ("Oh, where are the snows of yesteryear!"). Later, Dupin quotes the same Ballad in English. He also reads from the book a few lines of Edgar Poe's "The Raven."