Bourne are a series of three novels by Robert Ludlum based on the fictional spy Jason Bourne. The series has since been further extended by Eric Van Lustbader after the death of Robert Ludlum. When Eric Van Lustbader decided to stop writing the Bourne novels during the writing of The Bourne Nemesis, Brian Freeman was approached by the Ludlum estate to continue the stories of Jason Bourne. Source: Wikipedia (en)