 The book contains many instances of recursion and self-reference, where objects and ideas speak about or refer back to themselves.One is Quining, a term Hofstadter invented in homage to Willard Van Orman Quine, referring to programs that produce their own source code.Another is the presence of a fictional author in the index, Egbert B. Gebstadter, a man with initials E, G, and B and a surname that partially matches Hofstadter.