A Man Walks Into A Library And Asks The Librarian, "Do You Have Any Books On Pavlov's Dogs And Schrödinger's Cat?"

A Man Walks Into A Library And Asks The Librarian, "Do You Have Any Books On Pavlov's Dogs And Schrödinger's Cat?" <br><br>The librarian looks around and replies, "It rings a bell, but I'm not sure if it's here or not."