In his 1987 book, The Art of the Deal, Mr Trump explained what he saw as the keys to good negotiating. One of them was to be nice, but "fight back hard" if you think you're being treated unfairly. Another is to never show weakness. "The worst thing you can possibly do in a deal is seem desperate to make it," he writes. "That makes the other guy smell blood, and you're dead."

Trump's telephone un-diploma (bbc)